Apple Pay not accepting my bank Credit/Debit card told me must contact card issuer

Yes, I had the same issue before. You need to contact your bank by calling the number on the back of your debit or credit card, as the overseas payment may be locked or blocked due to too many failed attempts. In my case, my card was automatically blocked because I tried binding it 4-5 times, but the issue was resolved within 24hours after calling the bank and asking them to unlock overseas payments and unblock the card.

I hope this information helps.

Ask them to check ur account for

“Overseas Flag/Purchase Flag/Online Purchase Flag.”

and also did you try to restart your phone? also try to use ur mobile data after restart.

What country are you in and what bank issued the card?

Have you traveled recently, are your regions/countries set correctly?

Change the language and region on iPhone - Apple Support

Change your Apple ID country or region

Contact your bank and request the unlocking of overseas payments for your credit card. After that, try binding again.

What did the card issuer say when you contacted them?