Credit not passed

On my original contract, I had a 5gb data special for R199. In December I upgraded my phone. Since then I am being charged R349 every month for the 5Gb. I have spoken to 7 consultants and am waiting for 3 of their managers to phone me back, but still I have not received credits or refunds for the 3 months I have been charged extra. The data still hasn't been taken off my account which means I will need to get another credit end of April when the new debit order goes off. I really need to get hold of someone that can actually sort this out now!!!