Appalling experience

I took a contract on Dec 30 2021, I paid plus minus R3000 upfront and the agreement was that I'd get a discount, 1. Each month I must phone to let them knw that the discount was not added. 2. They always try to debit the original amount of the contract, not taking to consideration that I paid upfront. 3. Each month they promise that the issue is resolved but they always try to debit more than they should, 4. The banking details they debit from is not the same that I get my salty from, I always transfer the agreed amount into that account, it bounces each month because they always try to debit more, messing up my credit profile, it has been exactly 5 months trying to solve the same iss, I am tired, the amount we agreed on was 4248,99, not R380,00

I have gotten to a point where I hated the phone that I once liked. If this issue is not resolved I would have to return your phone and you you would need to give me my money back, I signed a contract for a reason and you are not adhering to the terms and conditions of my signed contract,

What happens now when it's the service provider that is breaching the contract.

Please resolve this