Failure to stick to contract

Vodacom upgraded two of my contract lines. They sold me Top up contracts at R460 per month. When they delivered the phones, I was informed that it was open line contracts that I was upgraded on. I was informed that the error cannot be corrected but that they would put soft locks on the benefits so that I will not be billed. They gave me 20 gigs of data on both lines and 150 mins for 24 months.... The 20 gigs of data was loaded for one month, and thereafter was not loaded again. I called into Vodacom and spoke to numerous consultants and they reloaded the benefits. I checked my Vodacom statement and realises that for over a year, I was incorrectly billed. I have for the pass two months been trying to call Vodacom to resolve the issue. I spoke to numerous consultants, ramario, siphiso, Masson. Masson in fact checked the system and acknowledged that the consultants loaded the benefits in the system erroneously and informed me that he will be forwarding this matter to the respective consultants and that they will make contact with me in 48 hours maximum... That was a month ago, no one has contacted me. I have recorded all the calls and documented all the consultants information that I spoke to. The last consultant I spoke to was Siphiso... That was last week Wednesday, Siphiso advised that he has logged the complaints and would call me the next day, this was not done. He also advised that the matter will be resloved by last week Friday 25 Feb 2022, this was not done. I spent hours explaining to each consultant what the problem is but to date consultant managed to resolve the problem. Yet, they expect me to pay my account every month.