No Service Delivery

I have been with CellC for the past 2 years. in this time, i have contacted the help desk many times complaining about the service. In many areas, i have no service or signal. many times, I have been on a call with a client and lost connection. many times, my phone is on, but a client will call and go straight to voicemail. I only receive the voicemail notification many hours later. I fail to understand that CellC will pay up to R20000 to buy one out of a contract, when even in Johannesburg, next to the main center, i had no signal. tried on 3 different phones.