Biling issue.

I upgrade my contract August 2013 and upgraded from A Blackberry to Samsung, I was using BIS the device was BIS compatible however when I upgraded BIS was not deactivated and I was not checking my statements last month I check it and realised that I been pay for BIS while I am using a Samsung that uses Data and i been billed for the past 22 months, since the call centre is on strike I went to a MTN store, the lady assisted but she assisted by deactivating the BIS on the 26.05.2015, however I was still charged again that very month, went back to the same MTN store in Newtown Junction this lady told me she will log my billing issue on the 05.06.2015, Ref no ***, when I call the call centre told after hold for 20 mins , Thato an agent logged another billing request, the network cut us off and i didn't get the ref no due to your poor network so can I please get my refund.