Then your banks staff is very poorly trained or their superiors want them ignorant. Either way the end result is your working with a bank that offers poor customer service and doesn’t care to offer support.
Apple cannot fix this issue. Apple is not a bank and does not approve, verify, authenticate or decline adding cards to Apple Wallet app. I’m surprised your bank’s customer service team aren’t aware of this.
When you enter card information into the Wallet app on your iPhone it’s encrypted on your iPhone. The data passes through Apple servers to the Payment Network Operator (Visa, MasterCard, American Express etc.) and is decoded and checked for authentication and if it passes goes to the issuing bank. The bank then decrypts the data and reviews all the information and declines or approves adding your card.
If approved the bank refers the data to a Token Service Provider (TSP) and the token is sent to Apple servers, which then add it to the Secure Element on your iPhone. Everything is anonymous to Apple and they have no knowledge about your approval or denial. Banks are prohibited by law from sharing the data.
If your bank rejects your request to add a card, you receive a notification to contact the bank or try again later.
What is a token? Tokens are an encrypted piece of code issued by the bank (very rarely) or a TSP (Token Service Provider). The token takes your actual card data and changes the account number, expiration date, security code etc. and changes the data (referred to as dynamic) for every transaction to prevent a scammer or merchant from making multiple charges with the same information. This is how Apple Pay works and prevents your data from being exposed to merchants and scammers. If your bank support staff doesn’t know what tokens are they are poorly trained or ignorant. In either case find a better bank. How Apple Pay operates does not change from country to country. It works one way or it’s not available in that country.
Fraud alerts are placed on accounts by either your bank or the PNO. If a PNO suspects fraud they can block your request from going to the bank for approval. Fraud department at the bank may be alerted by the PNO, but first tier support team is kept in dark and only present bank’s corporate policy, deny, deny, deny.