What problems have you had with your donation system?
Forgive my ignorance and that this message is off topic, I will be adding an online payment system to my site soon to allow people to buy my game and could benefit from your experiences.

Do you get fined if someone tries to pay you with a fraudulent credit card or is it that the payment seems to arrive then is mysteriously taken away?..

I REALLY don't understand why people donate using a fraudulent card anyway.. it's not like it's even their money to give away.. they get no real benefit from it, so why do they bother?. :?

I'm wondering, exactly what is it you're supposed to do in those curcumstances.. seems way beyond anything you (as the shop keeper) can control.

I hope you have better luck soon.