Payment methods

Apple, I need your help as soon as possible, I just bought an apple gift card and am trying to buy some Robux, but I need to verify a payment method, but I don’t have the Mastercard gift card that I used previously anymore, so I forgot the security code, I can’t remove that payment method, and if I wanted to add another, it has to be an actual card instead of my apple wallet, how could I get around this issue? Please be quick :(