Shocking service

My wi-fi modem battery has exploded, I went to Cell c in Melalane I was told by them that they cant help me, they will have to send the unit to the factory to get fixed which will be 6 weeks, they didnt have a loan unit for me. So what they were telling me is that I still have to pay my monthly wi-fi even though I cant use it. A so called senior manager phoned me and told me he would come back to me to date still nothing. All I want to do is cancell my contract due to non-performance and non-service from Cell C.