I tried adding funds to my account but when i clicked purchase it said (606 - This transaction is not authorized due to restrictions by your bank. Please use a different card or contact your bank for assistance) I’m wondering if i could get an answer for my question.
I’ve had that issue with my credit card. I had to call the number on the back and speak to them to let them know I approved transactions on this site.
We won’t know the real reason as everyone could have different issues.
You could contact support here - https://gameflip.zendesk.com/hc/en-us/requests/new.
In my opinion, I would advise contacting the number of the prepaid that you are using to ask and clarify why it can’t be used to purchase on gameflip.