I understand your frustration. But, we, the creators of the game, can't help with payment problems. We do not have access to anything. They just send us our cut of the money and that's all.
Now, let me tell you. And I'll be honest with you. You're the first one to tell us this. We sold thousands and thousands of copies of our games in more than one year here and you are the first one.
I'm not trying to excuse itch.io, just help you. I'm pretty sure it's not your purchase here that triggered the problem. I know the timing might make you feel 100% sure, but itch.io is the biggest indie platform to buy games. They are here for decades now.
Revisit your purchases. And I'm sorry again and wish you the best.