To prevent payments with credit cards for those users who have a payment request previously rejected and hide the payment gateway on frontend, you can enable the option Enable Blacklist.
After enabling this option, a new tab (Blacklist) will show in the plugin panel. Here you will find the list of users automatically added after their payment request failed.
To unban users, you can do it both singularly, through the option on the right side, or massively through the bulk actions. After unbanning users, they will still show on the blacklist and their status will change into Active.