Accounts double charge

I have been with Telkom for many years. And in the beginning of this year I've decided to move from contract to pre-paid with my cellphone and I still have my data contract. Firstly when I went to cancel my cellphone acc, I found out that my data contract when upgraded over the phone wasn't upgraded but was given a new contract, which made me to pay for 2 contract, but only using 1. I didn't want to start complaining and just canceled one. As for my cellphone contract, I've been given an outstanding amount to pay so that they can close it. I did that in February. However, 6 months later I get an invoice for the account I have paid and closed. I know for a fact that they won't close any account if there is an outstanding fees. And they can not prove anything that they didn't get paid. This is ridiculous as they've blocked my data account too. It's not my fault that they can't calculate and closed my account even if there was a payment due, and I know that I've paid for everything. The service is shocking as you can not even go to the shop to speak to someone, they've put you on a call with account department.