Stop *****ing from me

Mtn has continued to ***** money from me by billing me for a sim card and airtime that I didn't receive. For over 3 months I've been phoning in only to get told that they are waiting for a response from the relevant people. Who are those people?? And aren't there any other people who can intervene?? I think they are playing delay tactics while continuing to rob me. Worst part is if roles were reversed they wouldn't have hesitated in suspending my service.