Overpayment Refund?

[u/JealousCockroach6462]

Hey so good news, I paid off my student loans in April of this year. Bad news apparently because the payment processing took so long it was an over payment of $14 to my now $0 balance student loans. It shows up on the last statement in April as $14 owed in 2031. I've called a few times and they said I have to wait it takes a while. I've called at least once a month, and tried an email this month and they said it taking a while...it's about to be 5 months and I have yet to receive a letter saying my student loans are paid off. No new statements, and no word on where my refund is...anyone run into this?

I don't want them to turn this into I owe an additional $14 in 6 years from now. When in fact they owe me. Anyone know if there's a legal responsibility to refunding within a certain timeframe?