Cell C terrible service and signal

I am with Cell C Business and for over a year I have had really bad signal. I run a business off this line and almost every time I either receive or make a call, the call drops, or loses signal, and not to mention any whatsapp calls go dead for a few seconds, then drops completely and I have to dial back just to complete the conversation. I have notified Cell C numerous times and they always say that I need to follow a few steps which should sort out the problem. I followed all instructions and no joy, which tells me that their staff are untrained or just lazy to figure teh problem out. They then say that they are migrating my number to another network and things will get better... More lies. Calls are still dropped almost every single time. Their customer service agent have no clue whats going on and cannot fix the problem. They then give you a reference number that when you call back, tehy say that number does not exist. My contract has expired and seems that the best thing to do is to move to another network. The worst and most pathetic service provider i have ever had. In addition, i was told that they are using Vodacoms towers, this means that Vodacom customer get preference on a call. Maybe that exactly what is happening to me, but they wont just come out and say it as I assume people will cancel their service and move to another network.