Thousands of BNZ customers will need to change their automated payments after the bank decided to cancel its Mastercard bank cards ahead of their usual expiry date and replace them with Visa cards.

The bank has written to a first tranche of Advantage Classic Mastercard customers giving them six weeks' notice that their Mastercard credit cards will stop working on March 12.

Customers will be issued with Visa cards instead.

Other BNZ Mastercard customers will be contacted as the replacement programme progresses.

The replacement cards appear to have few advantages for customers, according to the letters BNZ has sent out.

Fees and rewards programmes are unchanged.

The Visa cards are compatible with Apple Pay and Google Pay, but have the slight disadvantage that service fees on foreign currency transactions will not be credited if purchases are refunded.

Spokesman Sam Durbin said BNZ believed the replacement Visa cards also had better security features "and simpler processes for customers wanting a new card".

"I wouldn't say it only benefits the bank.

"They have quite an in-depth and sophisticated analytics platform that helps detect and stop fraud," he said.

BNZ's letters noted that customers would need to update any regular payments that came from their credit cards.

These could include the likes of utility and insurance bills and subscriptions to online services such as Spotify and Netflix.

"You will need to update any regular payments from your card account and anywhere you've saved your card details before 12 March 2020, after which time your old card will stop working," BNZ's letters said.

Those letters provided no explanation for the card change, other than that BNZ was "simplifying its range", and made no apology for the inconvenience.

BNZ only stopped issuing new Mastercards on November 20.

Durbin said an apology for the inconvenience would be included in future mail-outs as the card replacement programme progressed. 

"The vast majority of our customers are already on Visa cards – about 80 per cent of all our cards are Visa – so this change affects a relatively small proportion," he said.

BNZ was not immediately able to clarify where liability might lie if a customer missed the notification letter and as a result failed to update their insurance payments.

The bank had to notify customers of the card replacement programme by letter rather than email for regulatory reasons, Durbin said.

It is not the first time some BNZ customers have had to go through the rigmarole.

BNZ issued "Advantage" credit cards to replace all of its 100,000-plus GlobalPlus credit cards in 2015, ahead of their normal expiration dates, after Air New Zealand terminated its Airpoints reward scheme with the bank.

The changed expiration dates meant customers in some cases had to update their automatic payments.