Incorrect Billing

I received a email from Dstv on the 25/06 and the contain of the email was that if you upgrade to the premium package you will save money for the next 3 months. I phoned the call centre spoke to a agent advise him about the email, he upgraded my package and still confirm that I will pay round about R729 for the next 3 months. Payment was made on the 30/6. On Monday the 26/07 I wanted to pay my account to my surprise my balance showed R1120. I immediately phoned the call centre and explain to the agent my situation the agent confirm that she will forward my matter to billing as this was incorrect and they will get back to me. On the 29/07 no one responded and then I phoned the call send back again, I had to explain myself again to the agent I even email the agent the email that dstv send with the offer, she then puts me on hold for 40mins, after that spoke to a guy named Sebastian and he confirmed that he is the manager. He confirm that he will escalate my matter to the billing department and he will give me a call back today. Still no response from him. I want to pay my account but they are not getting back to me in order for me to do so.

Disappointing in the service