10 It appears that the direct debit authority form was completed and provided to Challenger by Mr Angelo Ferella, but he did not give evidence in the proceedings. There was a second version of the authority in evidence before me on which the BSB number is written clearly as ending in a zero, but the number is incomplete, being written as simply "2000" (the correct number was 06 2000). In any event, neither party suggested that the second version of the form was ever sent to Challenger. Challenger sought to rely on it in the proceedings as an "admission" by its author that the number in the form originally sent looked like a six, but I did not admit it on that basis (T50 to 51).
11 Pursuant to clause 6.2(1) of the loan agreement (read together with clause 29(17) of the definitions clause), the first payment of interest was due on 1 November 2006. Challenger attempted to obtain the interest payment by direct debit on that date, without success. It is now clear that the reason payment was not obtained is that Challenger had entered the wrong BSB number. It appears, however, that the information provided to Challenger by its bank, Westpac Banking Corporation, did not include details as to why the direct debit failed. Challenger simply received an electronic file in respect of all borrower accounts identifying which payments had been received and which had not. It did not know that the direct debit failed because the account name and account number did not match.
12 On 6 November 2006, Challenger wrote to Agusta in the following terms:
"Our bank has advised us that your periodical direct debit for November in the sum of $4,143.42 has been dishonoured. This may be due to invalid bank account details provided to us, the closure of your direct debit facility or that there were insufficient or uncleared funds in your bank account.
We request that you forward a cheque made payable to Perpetual Trustee Company Limited to us, including a $20 dishonour fee that has been debited to your account.
Please note that interest payments are due on the 1 st of each month and payable within 7 days. If payment is received after this date, interest will be applied at the higher rate."
13 Agusta paid the sum of $4,143.42 by cheque and that amount was credited to Agusta's loan account on 8 November 2006. That pattern continued for several months until the error as to the BSB number was discovered. Some of the cheques, however, were not credited to Agusta's account within 7 days after the first day of the month. Challenger contends that those payments were not made within the time allowed under clause 6.3(2) and, accordingly, that interest for the periods pertaining to those payments was calculable at the higher rate.
14 Correspondence sent to Challenger during that period from Ms Tiziana Ferella on behalf of Agusta discloses that Agusta was proceeding on the basis that Challenger should not attempt to obtain payment in accordance with the direct debit until the 7th day of each month, because Agusta received its funds from the tenants of the property on the sixth day of each month. In a letter dated 27 March 2007 to Mr Paul Williams at Challenger, Ms Ferella stated:
"I note with conviction, I have reviewed the file the account is up to date it is disputed that we are indebted in the sum of $3,987.96, please go back and check your figures because you are incorrect, also please note as you were told on several occasions you are not able to draw the funds until the 7 th of each month because that is when the funds are placed in the bank by the tenants."
15 That position was reiterated in a letter dated 22 April 2007 when Ms Ferella stated:
"You have been notified on many occasions not to try and draw down funds from our account in regards to the facility in place on the first day of the month until we have resolved the funds being received from the tenants, because we receive all payments on the sixth of every month in arrears, we are finally coming to a stage where this will be resolved in which you will be able to draw the funds on the first day of the month from now on."
16 The error in respect of the BSB number was finally discovered in early May 2007. On 9 May 2007, Ms Ferella wrote to Mr Williams to inform him that, according to her bank, there had been no attempt to deduct any moneys from the relevant account by periodic payment during the relevant period. Ms Ferella stated that her bank had suggested that "the error must be at [Challenger's] end" because there had been no reversals for insufficient funds in respect of any withdrawals on the account from 1 January 2007 to 1 May 2007, nor indeed any attempt to obtain a debit from the account by periodic payment.
17 On 14 May 2007, Ms Fiona Giorgi, an employee of Challenger, made an entry in the loan journal in respect of Agusta's loan in the following terms:
"Loan bank details changed from (062-006 [followed by account number]) to (062-000 [followed by account number])."
18 Ms Giorgi could not recall how the information as to the correct number had been conveyed to her. After that date, the monthly interest payments were received within the 8 days allowed for payment at the lower rate by means of direct debit in accordance with the authority Agusta had intended to grant at the outset of the loan. An account statement tendered by Challenger (exhibit B) indicates that those payments continued until February 2008. However, Challenger took the view that Agusta was still in default under the loan agreement (due to its failure to make some of the earlier interest payments on time) and continued to debit the loan account at the end of each month with additional interest reflecting the increment for the higher rate. So far as Challenger was concerned, the account continued to be in arrears because Agusta had not paid that additional interest.
19 On 10 July 2007, Challenger sent Agusta a notice of arrears claiming an amount of $13,515.16. A copy of the "current interest statement" for the account was attached to that notice but that statement opens with a balance in arrears of $6,471.13 as at 11 April 2007 and it is therefore not possible to be certain as to the precise composition of the amount claimed. It appears to represent the increment for interest calculated at the higher rate over five months.
20 Ms Ferella responded by disputing that Challenger was entitled to the higher interest rate, contending that Challenger had been given the account number regarding periodic payment when the facility commenced. That letter was sent on 21 July 2007. On 31 July 2007, Challenger served a notice on Agusta pursuant to s 57(2)(b) of the Real Property Act 1900. Ms Ferella again wrote disputing that Agusta was in default under the mortgage. Her letter concluded with an invitation to Challenger's solicitors to commence proceedings if they considered they "have a case". On 3 October 2007, Challenger did commence proceedings, seeking an order for possession of the property and leave to issue a writ of possession. The statement of claim alleged that the arrears unpaid as at 10 September 2007 were $18,456.14.