Billing

I renewed my contact but only the sim for R100 per month never had problems before this contract. They have been deducting Last year for a app that they said i used after stuggling with them i said they must block the sim again for any other billing Just like i said when i renewed the contract (only sim card). Now i was billed in January again and when i logged a case they never came back to me, i went into telkom and they said that they Will Phone me. No response back yet so i Phoned today. They said they billed me January for Last year june and july for other apps i used. This is not acceptable. We as customers cant Just keep on paying and then after a couple of months get an invoice and pay for apps they said we used 6 months ago and i didnt even received feedback how this could have happend in the 1st place if this is only a sim that cant go over the limit of R100.