Nedbank Loan never goes down no matter what you pay

Nedbank is the worst bank ever l have been paying for a personal loan for years l finished other credits already and only Nedbank doesn’t go down at all no difference even if l pay a lot of money towards and it’s been over 6 years when l call and ask what’s happening they tell me charges go up and down every month that’s why. The guy l spoke to told me just keep paying even if it doesn’t go down a bit just pay. Am disgusted with Nedbank never ever use this ugly bank l regret ever doing this with them.