VERY BAD SERVICE

I took out a contract with Telkom for R199-00 per month at the East Rand Mall after two months I now get a statement for over R2424.29 Telkom acknowledge that a mistake was made on their side by the consultant but I am still liable for the mistake you cannot explain anything to them they keep on saying "sorry our mistake" but I must pay I have a signed contract with me POOR POOR POOR SERVICE WILL NEVER ADVICE ANYBODY TO GO TO TELKOM