Unexplainable fees

I have had a contract with Vodacom since 2013 and previously had a prepaid sim. I have never had any complaints with them until recently when amounts that even the employees at the Vodacom outlets could not explain. According to the statements I get that I could not make sense of nor could the employees, I have been getting charged for two insurances and data that I am not getting. When they do call client care no one wants to help them as they keep saying there is no accounts department. When they called several times they eventually helped but still I got an sms regarding something that was not the topic of discussion. I had paid my bill and also paid ahead meaning that Vodacom was owing me funds. Then I get an sms stating that I'm in arrears of R274, which made no sense to me. It seems I am also getting a charge fee for a returned debit order of which does not make sense because my account is set to a prepaid payment of which I make EFT payments. I went to the branch for them to assist me as now my calls have been barred so I can not make any outgoing calls. They do not know what is going on with my account either. I used to believe this was the best network but if I am going to get such treatment after years of being a loyal client then I guess I need to just change networks. The one month I was sent my bill which reflected that I didn't owe anything the following month I was charged double but with amounts that don't even add up nor are they the same amounts as in the contract.