I think my bank stole 54 cents from me

There has finally been a resolution to my auto financing problem. To sum up, the bank decided I didn't have insurance charged me for some of their own, a total of $83.87 that they helped themselves to out of my last payment without telling me (thankfully I always check my payments online).

After faxing over the appropriate paperwork showing no lapse in insurance coverage, it took 33 days to get it corrected - oddly, a day before my next payment was due. $83.87 has been credited to my account and correctly applied to the balance of the loan (the interest was unaffected).

But here's the thing. The insurance payment they took left me with an inflated principle from 8/3 to 9/5. An inflated principle $84 more than it should have. Thus this next payment in which they are going to charge me interest, based on the 33 day billing cycle, is going to be more than I should owe. By my calculation that is a full gain to the bank of 54 cents.

I wonder why it took a whole month to get the problem corrected? I guess they had 54 little incentives to drag their feet.