No 3G Network for over a week

I am sick and tired of Cell C. I have three contracts with you and every area of customer service is beyond pathetic. Five months ago I had a problem with a blackberry device that I took with Cell C, it took two months for the problem to be addressed. It put me through inconvenience and unnecessary costs! I was then given a \refurbished"device. NOW this dam refurbished device is full of ****! most of my calls go on voicemail and there is hardly any 3G coverage. I tested the sim on another device and its fine. I am really sick of this service so can someone tell me what the hell to do!! is it the network or what? I doubt its the network because everywhere I go I have the same dam network issue. Can someone PLEASE reply"""