What worries me now

A friend told me that he had a credit card with a balance on it. He refinanced his house and used the money to pay off several accounts, including that one. He called the bank and they told him the balance, and he sent a check, but the next statement had an interest charge of about 12 cents.

What worries me is that the Fraud Department will clear out the Fraudulent transaction, but there will be some interest charge on the March account after I sent them the check to cover the rest of the balance. Then the system will recalculate and charge me $39 late fees for each month since then that I never paid. In theory, I could have a bill for over $200.

Or the fraud guy could have completely messed up, and even without the fraud transaction, there's an outstanding balance, and once again I'm looking at about $200 of charges.