Bank robber

Back at the end of November I went to the bank and paid out my credit line.
At least I thought I did. Actually I had just paid the current balance. A week later I had an interest charge. Today I called the bank about it to complain.
However, back then, the teller was somewhat new at the job and had made another mistake. When I did the paying out, at the same time I withdrew $60 from my chequing account. And while I did receive the cash in my hand, it seems $60 also got credited towards my credit line.
I called to complain about that too.
They appreciated my honesty. But in the end, their advice was to take the money and run. After this long they were going to write it off. The stinging remark was that the guy on the phone said, to justify this bounty, that I was a long time customer and that they had made a lot of money off of me.
I don’t like to think of banks making a lot of money off me.