Disappointed client by MFC

I bought a car from MFC in 2020, and in August of 2023, i started paying extra towards my car, and this month i asked that they review my interest my is ridiculous high at 16% , they refused saying that they can't restructure my interest because they did so in August of 2023, when i thought that i was doing right by the bank and me it has come back to bite me because i was not told that by paying extra i was restructuring and that asking for a review is also called restructuring 3