********* and poor service delivery

My contract was up for an upgrade in 2014. I received a new handset that was faulty. The consultants at the branch acknowledged that the handset was faulty and followed the normal procedure of sending it to the relevant department for repairs. The handset was returned but the same problem persisted. We ended up taking back the handset three times and on each occasion followed exactly the same process and each time the consultants agreed that the handset was faulty. During this time we were still being billed as normal. On the fourth occasion we took the handset back and refused to continue in the same fashion, we told the consultant that we would like to cancel the contract, he in turn said that this could not be done from the branch and we would have to contact the call centre. We did this on several occasions and were given the run around. Without any notice the sim card stopped working as of May 2015. We were then under then impression that the contract was cancelled. We were then debited again in June for the premium. We have no phone , no sim card but are still paying, for what I have no idea. Any assistance in resolving this issue would be highly appreciated.