Unfair Loan Restructuring

I took a loan on February 2024 for a period of 48 months (4 year's) while I was receiving my salary at another bank and all was well. A few months later I walked into the branch and I was convinced to switch my salary to Capitec and this was done incorrectly by the branch consultant because come the salary date the debit order bounced at the other bank where my salary was no longer being deposited and this obviously reflected negatively in my name. Out of concern I consult the bank and I am told to call the credit department for an arrangement which I did. This is when my loan was restructured to 84 months, mind you I had only defaulted for less than one month, due to the branch fault. This I'm told cannot be changed because I "agreed" on the phone call and I refuse to accept this because I would not have been in this position in the first place if they did not mess up my salary switch dates. I cannot pay the same instalment and interest for double the initial agreed term of the loan all because I defaulted for less than a month(not by my own fault even).