UDU handed over to MDC Collections when NO payment was skipped. Interest on future transactions added.

I signed for a loan with UDU Financial Services - and each and every payment went through with no issue whatever. Although they do not deduct the amount on the day that I specified in the agreement/contract... But that is not the issue. I have half of the repayment term left on the loan and want to settle it... But the people that called me was MDC Collection Attorneys.. And the settlement amount has future interest calculated in. Is it not against the law to add interest for future payments when the account is fully up to date?

No response from either UDU or MDC... As expected.