Cancellation of Contract

My contract already expired in June 2016, they called me and ask if I want to carry on or cancel, I said cancel, until today they are still taking money, I returned it and then they use another account number to take the money. I went into the cell c shop in Pietersburg to cancel but they said they don't do cancellations there. I went on Cell C website emailed them but still no luck. I need the right email address for cancellations please. It's the second time I take a Cell C contract and the first time they did the same thing, won't ever use Cell C again.