Irate client

I have a data contract with Cell C for the past 15 months. The Sim Card stopped working in February 2023 and I called Cell C to report it but the consultant wasn't very helpful and I ended up dropping the call. I called again this week and got throughto a consultant who told me to visit a Cell C outlet to do a sim swap. My issue is the router is in Free State as I took the contract for my 13 year old son. Why do I have to run around doing sim swaps but when I initially signed up for the contract the sim card was delivered to me. The sim swap process is complicated and I'm working 6 days a week I can't go to a Cell C store. Since February I'm still being billed for a sim card that's not working. I need Cell C to sort this out and also refund me for the 3 months that I haven't been using the allocated data or else I'm cancelling my contract. The number in question is ***.