Cell C's Network , and their breach of contract

Took a Contract with Cell C in Pavillion in May 2014. At the time Cell C, was the most affordable network and contract for me. After I took the contract, I realised that I never picked up 3G signal at home. I lodged a complaint which was of no help to me. A guy was supposed to come home to test the network and he never, so eventually after I got so fed up I decided to leave it as I could roam on Vodacom's network and get signal for the period when I was at home. However about 2 weeks back I noticed the Signal while roaming on Vodacom's network to have been completely gone. So I had phoned customer care and lodged a complaint AGAIN and the guy tells me that Cell C no longer allows roaming on Vodacom's network anymore. So what network am I supposed to use now??? I am paying R530 a month for a network I cannot use. I have paid almost 75 % of the contract and I have abided on my side of the contract. Now CellC is not able to abide by their's! I am absolutely fed up with Cell C and i urge customers and potential customers to consider alternative options as network is bad!. Cell C better come up with an idea to rectify matter or i will make sure I take the matter to the highest level!