Bad service

I'm very angry and disappointed on cell c, September I returned their wifi router and also canceled the contract but they keep billing me. Last month November they also not debited their money for my other cell phone contract I have with them. Now they have suspended all my lines and if I'm calling them to make an arrangement for the debit order they are refusing and saying they want their money now or they won't open my lines. So I've decided to cancel everything and go to another service provider who can provide better service then Cell C