Account still not closed

I've been to the branch at Lakeside mall to give my 1 months notice at end of January 2015, however I was still billed. I went to the Alberton branch 3 months later to give notice yet again. I was promised to be credited for the two months I paid after giving the notice, which I was, just to be debited yet again on a monthly basis and again I'm receiving a invoice to pay. During all these months trying the call Centre is an absolute waste, because you hold on forever and never get the opportunity to speak to someone. This means that I will have to use my time to go back to a branch yet again...