HSBC customers have complained the bank has made it more difficult to draw out money abroad.
Many on business trips or holidays have said they were unable to get their hands on their cash from ATM machines.
That's because the bank has switched to chip-embedded cards that connect to a single global payment network.
Previously, access was provided to the Link or Plus networks. Plus is owned by Visa and claims to have access to 1 million ATMs in 170 countries. But HSBC has chosen China's UnionPay as its network provider for the new chip cards.
One Hong Kong resident told the Sunday Morning Post: "Since the issuing of new cards, I have been in London, Istanbul, Tokyo, Morocco, Vancouver, Vienna and Paris.
"I had no joy getting cash in any of them. It always said card error, card invalid, or simply spit the card back out with no explanation."
HSBC did not reply when asked whether changing from Plus and Link would mean customers would have access to fewer banks worldwide.
The Monetary Authority has instructed all banks in Hong Kong to adopt the chip-based technology for ATM cards.
The new cards have an embedded microchip on the face, but retain the magnetic stripe on the back. The new technology is designed to make it harder for criminals to use stolen data to manufacture fake cards.
But in adopting the technology, several major banks forced customers onto the UnionPay network this year, instead of the Plus system.
The UnionPay network was launched on the mainland in 2002 and is operated under the supervision of the People's Bank of China. UnionPay cards are accepted at merchants and ATMs in 141 countries.
But Hongkongers say UnionPay is a poor substitute for Plus and Link, as it is not recognised by as many banks worldwide.
UnionPay-friendly terminals outside Asia can be difficult to find. Even if you do locate one, it may not have been updated to handle the new cards.
HSBC said customers would encounter problems if they had not yet activated their ATM overseas cash withdrawal limit - a new procedure put in place by the bank to improve security.
But customers said it was the change from using the Plus and Link networks to UnionPay that was causing the problems. An Australian resident in Hong Kong said only National Bank, Citibank and HSBC would accept the card in his home country.
An industry source said HSBC put the networks out to tender and decided which one to use based on the best deal.
An HSBC spokesman said: "For security reasons, we are allowed to link to only one pay system - we use UnionPay."
He added that ATM card customers can withdraw cash from all HSBC ATMs in the world - except in Argentina, Brazil, France, Greece, Malta, New Zealand, Panama and Turkey - as well as from ATMs covered by the UnionPay network.
The bank aims to complete the card replacement process by the end of March next year.
A Monetary Authority spokesman said it was a purely commercial decision for a bank to choose which network they used.