Contract cancelled, but still deducting

I have been struggling to cancel a Wi-Fi contract, that has never worked, finally got it cancelled on 13/2/2014, and was promised a refund as the service only worked 1 day. This month another subscription was deducted from the bank account and now this needs to be refunded as well. If the service only worked for a few hours after installation (22/10/2014), problem was constantly reported and not fixed, more was deducted than the original R499 that was signed for surely this constitutes theft??