Bridge off contract

Cell C billing wrong I upgraded 3 handsets in December 2015 Boksurg East rand mall and the the lady cancelled 3 x Blackberry BIS that was going off automatically. In January I was billed for the BIS again but we are using the new handsets LG G4 Stylus I went on HELLO PETER and a Cell C agent assisted and end off Jan 2016 I paid R1057-00 In Feb 2016 I was billed again for the BIS and when I phoned Cell C the lady promised over the phone she cancelled the BIS and they will refund me R189-98 NO JOY the billed me again for the BIS PLEASE CAN SOMEBODY ASIST OR MUST I GO FOR LEGAL ACTION AND SUE WITH COST BECAUSE this is getting out off hand now I phoned 084 143 and promisses were made