Can't make any calls or use my data on vodacom contract

Can't make any calls or use my data.

I have been a vodacom client for the past 13 years, I am currently on a top up contract. I haven't been able to make any calls since 6 September 2018. I have been to 2 separate branches and the tech guys haven't been able to find any problems on my phone. I have called the call centre multiple times and they haven't been able to fix the problem. It has been more two weeks and I am still being charged for my contract even though I can't make any call. Why should I keep paying if for a product I can't use?