African bank inconsistency in monthly payments

I made a deposit of 70000 in 2021 February trying to reduce my monthly installment. Little did I know that it wouldn’t assist in changing my ITC profile with the new installment I arranged telephonically with their consultant. They are struggling to stick to agreed payment & that’s really inconveniencing financially. If I reverse the debit order I will be regarded as a bad payer. To stand in queues at center is time consuming. Why did they receive my money but struggle to review the contract or change payment on my ITC profile. The only proof I have is from my bank that I paid the amount & no contract from African bank confirming my deposit of cash.