Hi there Baggÿ,
Sorry to hear you’ve run into some problems trying to make a purchase.
In situations like this, it almost always comes down to the transaction being declined by your payment provider.
Not even trying to make a purchase, even when you go to set it up as a payment method a card check is performed and if that is also being rejected it would be causing the issues you’re seeing (which would be pretty common once there are several previous failed attempts)
You can read more about this here, though from your description it sounds like you already tried the other troubleshooting steps and at this point I’d recommend you reach out to your payment provider directly for more info and assistance.
Best of luck and I hope you can get it sorted so you can complete the order you wanted!