No feedback for 8months

I app**** for a mobile WIFI device November 2014. All went well until the first payment date. I noticed that the monthly debit order was going off the wrong account (a closed account) I went into the Telkom branch in Feb 2015 and fixed the problem. Still they debited the wrong account. Not once have I received a call, sms, email or post mail regarding the fact that the money that needs to be debited from my account has been bouncing back as they have not changed the details on their system to debit the RIGHT account. I have gone into this Telkom branch 4 or 5 times now (only given 1 ref number) and no one has bothered to fix the problem. In May 2015 I went back to try and speak to someone in charge, I was unsuccessful. They promised to get someone to contact me. By this time they have suspended my WIFI and say I owe more than R800 now where my monthly instalment should be R129. I have asked why I need to pay the full amount of R800 when they never fixed the problem the first time I came in. They said all they can do is get someone to contact me. I am still waiting, with NO WIFI!! I have to constantly contact them and I am getting NO WHERE!