Legal Question in Credit and Debt Law in Pennsylvania

No. Why would it be illegal? People bounce payments all the time. Did the borrower intentionally write a bad check (or the online equivalent) and then proceed to charge more without intending to pay? If so, that might be theft. Otherwise, I don't see criminal conduct in just bouncing a check.

The problem will be that because the payment was reversed, there really was no payment and the credit card company will hit the borrower with late fees and any other fees they can dream up.

I don't understand the rest of your comments. What is the credit card balance? Telling me that a $700 payment was made does not really tell me anything. Was the balance paid off in full? When the payment bounced, what happened then? Obviously the borrower made the payment and spent another $70 but what is the $100 referring to? Even if the borrower paid $100 (enough to cover the $70 charge and some of the late fees) there is still $700 owing if that was the payment plus any other fees.