Pathetic service on upgrading !!!!

I've been a client of cell c for over four years. Never skipped a payment or nothing. I'm due for upgrade but they don't want to upgrade because two debit orders reversed, October and November 2016, this was not for lack of trying to change details, I tried numerous times but they wouldn't assist me because I'm not the account holder I explained numerous times to them the account holder isn't in the country and we need to change banking details but they wouldn't assist me, anyway both times the debit order reversed I went and paid directly immediately, we have never been in arrears. This months payment went off normally because I activated the accou t again just for this debit order. But now we must prove ourselves for three months really we not in arrears never have been, so what must I prove ? When I went to the store that helped me they say it is by credit and they are investigating if I tried changing details or not. REALLY DO YOU THINK WHEN I CALLED THE AGENT THAT TOOK THE CALLS NOTED THEY COULDNT HELP ME WITH MY REQUEST !!! MAYBE ITS TIME TO MOVE TO ANOTHER SERVICE PROVIDER ?