Overcharging clients

I have upgraded my contract in December 2015. It was changed from R 99pm to R 139pm (DATA contract). I was happy with the service before the upgrade but very disappointed by what's happening now. I received my first invoice the 2nd of Jan 2016 and was billed R 788.00. I called in and they advised that bill was incorrect. I was refunded 2 months later BUT my invoice is still incorrect. I have some add on bundle of R 349 together with my normal bill of R 139, which I am paying R 488.00 pm. I have requested so many times to remove the \add on\" of R349 but they seem not to understand my query. I have received many reference numbers for all the calls I logged (I even did it on face book), but my query is still not resolved. I am paying so much for Telkom right now which is not in my budget. I can unpay the debit from my bank account but then my number gets cut. Unpaid items do reflect bad on a persons credit record. TELKOM SORT OUT MY QUERY PLEASE!!!"