Why is my card keep asking me to update but whenever i do it’s still being declined or it’s not working

when i try buy things off my phone like let’s say snapchat+ i will click the payment and it will do the face ID like normal, then it will come up with transaction failed and ask me to update my card, but whenever i put the correct details in it still dosent work, i’ve been to the bank but they only done it on the wallet for apple pay, and not through the settings. it is quite frustrating though especially if i want to buy something. what do i do .? why is my card keep being declined and keep saying failed although all the information is correct .?