over charging for data useage

I WAS CHARGED R2 652.03 ON MY JUNE 2015 ACCOUNT. HOWEVER MY AVERAGE BILLING AMOUNT IS R1251.53. THE DATA VALUE ON THAT PARTICULAR STATEMENT IS R998.79. I HAVE NEVER USED THAT MUCH DATA, EVER. I ASKED FOR PROOF OF THAT DATA USAGE BUT HAD TO PAY THE ACCOUNT IN ORDER NOT TO BE DISCONNECTED. THEY SAID IT WOULD TAKE 6-8 WEEKS TO GET A REPLY. 3 MONTHS HAVE NOW PASSED AND I HAVE NOT RECEIVED ANY FEEDBACK. I HAVE ASKED AUTOPAGE FOR A FOLLOW UP AND HAVE NOT RECEIVED A REPLY. ACCORDING TO MY REPORT HISTORY ALL TASKS HAVE BEEN COMPLETED. I HAVE BEEN A LOYAL CUSTOMER FOR MANY YEARS AND AM DISAPPOINTED AT THIS COMPLETE DISREGARD OF MY COMPLAINT.