Telkom Mobile is useless - Do not use them

Telkom is the most useless cellphone network ever. I cancelled my cell phone contract on the 24th of October. Then all of the sudden in February of this year they have started to debit my account again. I have letters from Telkom confirming that the account has been settled and paid off. From February they have tried to collect every month, and I then have to reverse and remind them that my account is debited. I have been on a call to them now again for 40 minutes, and they could not resolve the issue. The most useless people I have ever had to deal with.