Bad service and billing error

I contacted Mondo in January to get a Telkom simcard and went through the entire process and I agreed to their terms and conditions. However when the simcard was delivered I had already purchased another SIM to which I would port my number to. A mistake was made and my number was posted to the incorrect sim. So I contacted Mind i to cancel the contract and was told I need to get in touch with Telkom in order for that to be done and I did exactly that. Mind you that the contract was cancelled during the cooling period which is from the day of delivery to 6 days and I cancelled on the 3rd day. I went to a Telkom shop to purchase another SIM and called the call centre and was able to retrieve my number to the new simcard. I started receiving billing letters and I made an inquiry on the 15/03/2018 and spoke to Thando Zwane who reassured me that it was indeed cancelled. Received another billing letter and I called in again on the 26/03/2018 this time i spoke to Gugu, she informed me that the case was not logged and was told to do a follow up after 72 hours. I also wanted to get my refunds as they have been debiting amounts on my account. How can you have debit active for a cancelled contract? I have been calling them ever since and I've had numerous reference numbers and I'm sick of it cause you hear something different with every agent. They have all been telling me that the contract has been cancelled and I've been waiting for feedback and my refund but now to my surprise I've been handed over to their attorneys saying that my account is in errors.