Interest on paid debt, how long will this go on?

Factual Questions
1

So I’ve been paying two of my school related debts for the past year on my own, apparently I missed one that was $500 back in the 90’s and had sky rocket to $2000 by last year.

They garnished my wages since they were apparently sending mail to some past address for ages and I had no clue. Most likely, while investigating my other two minor debts I must have given these people enough personal info to find my employer. Anyway, the debt was paid off by me through my employer just last month. Now my employer gets yet another garnishment order for $50 in “interests accrued” while paying off the debt.

What the heck? why wasn’t that included in the total in the first place? What are they going to do next, charge me the $.05 in
interest accrued" while I paid these 50? And then the .01 that was accrued while I payed off those $.05?

I’m going to write a letter to the officer in charge of the debt, including a check for the $50, but what else can I expect from this?

2

I hate that. Basically, you have to call them and get a “payoff amount.” They’ll tell you $X.00 paid by specified date, or it will go up to $X.05 after that date.

I got into it with a credit card company over the never ending interest. It was no big deal on my house, but for some reason, the small amount on a credit card was a pain in the ass.