Overcharging on Invoice

I upgraded my contract in Jan 2016 from R 269.00 (5 gb Data plan) to R 199.00 ( Smart Plan 100 + Huawei P8 Lite). From then onwards i am getting my new invoice for R 548.00 which i was suppose to get only R 199 each month. I phoned the Call Center a few times (Case no: ***6), Every time they are saying that the claim will be handed over to the claim manager and he will get back to me . But untill now i did get any call from the Telkom. Raja. ***