Telkom Mobile... Cant cancel contract

Oh Telkom... you've done it again... 5 months ago my Telkom Mobile contract sim card suddenly stopped working in my phone after three sim swaps, still not working.<br> I tried a V*dac*m simcard in the phone and it works just fine. After 5 months of sim swaps, over 10 hours on the phone and waiting for technicians still no luck ( Still paying my bill of R1500 every month.) During the 5 months I have not been able to make one call or send a single sms. Ive tried to cancel the contract with no luck??? I'm at my wills end. Please if you know of anyone that has any authority at Telkom Mobile that could help me?