Apple application purchases

I am having trouble with an Apple app, Topps Marvel collect. I love the app and have many cards that I have purchased already. I DO NOT WANT TO LOSE MY CARDS! However, I have already contacted my Wells Fargo bank a dozen times for errors in purchases. The problem is that sometimes the app purchase feature does not give me the diamonds to get more cards after a purchase is made. The phone marks error and I have filed claims for refund. Recently, the app does not let me purchase anything at all as if there is some kind of block. It has to do with Apple because I have already spoken to my bank on these issues and the problem persists. So what do I do if I see cards I would like to own?

concerned

Luis Ramirez