BNZ claims the staff member who described the misconduct as widespread was incorrect and that its online banking service was not partially offline, as the bank stated on its website.
BNZ says it fixed a flaw that saw some customers charged twice for credit and debit card transactions.
The bank said it learned on Saturday that some debit and credit card transactions made on Thursday were duplicated on Friday.
Some customers reported that the debit error left them with no money in their accounts.
BNZ spokesman Sam Durbin said customers would be refunded any overdraft fees or charges that may have been charged to their accounts as a result of the error.
* BNZ hit by second outage in four days
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* Glitch saw transactions double across mobile and internet banking
If clients suffered further losses as a result of the misconduct, they should contact BNZ who would consider them “on a case-by-case basis”, he said.
“If a client is missing out of pocket for whatever reason, they should definitely tell us and we’ll see what we can do about it, because I’m sure we can find something.”
But Durbin did not guarantee that BNZ would compensate customers for any consequential loss.
“I can’t give a blanket ‘yes’ or a blanket ‘no’,” he said, adding that customers might have had other ways to make payments if they had been declined. by BNZ.
BNZ said on Facebook that the problem was “widespread” and its contact center was “hammered” as people reached out to the bank for help.
Durbin said information was provided in error by a staff member, but confirmed wait times for calls skyrocketed to around an hour.
BNZ was unable to immediately calculate how many customers were affected by the outage, but it only affected a portion of transactions made on Thursday, he said.
The bank was still investigating the cause of the problem, but it had to do with how the bank first tests whether there are enough funds in an account to authorize a transaction, before performing that transaction separately.
BNZ had indicated on its website that it was also experiencing a partial outage of its internet and mobile banking services, but Durbin said that had not been the case.
Instead, it was a message that popped up automatically when BNZ used its website to communicate a problem with its services, he said.
The bank has previously encountered a problem with duplicate transactions in 2018 and again in April, when it was hit twice by technical issues that also prevented people from making card payments.