Cancelled BUT still CHARGED!!

About just under 2 months ago, I received a call advising me that because I have been a vodacom customer for more than 10 years I am entitled to a free wifi router with no cost, this was my understanding, only to discover, once the router arrived that it was in fact a new data contract, over and above the 3 cell fone contracts I already have. I immediately contact vodacom and arrange for everything to be returned, including the route with packaging. In the next month, I receive an invoice that I will be billed for the contract. I contact vodacom and they advise that the consultant "should have advised me" to report a cancelled deal as well, the consultant DID NOT....how is a client to know all the nitty gritty if not advised, for evidence, please pull/draw all recorded calls of my conversations. I then do as I am told and cancel the deal telephonically, low and behold, I check my bank statement and I am billed. Please reverse this error today....NOT longer and have someone call me ASAP!!!!