Account problems

My account with Vodacom has been a nightmare since day one. Recently, I have come to the end of my contract. I phoned in to confirm that it would not be continued. I received an sms stating that I owe Vodacom R700. When I phoned to query this the gentleman informed me that I needed to pay R1052. He stated that I haven't paid for May and June and that they are billing me for July as well. I asked for figures that he could not give me. My monthly payment is only R206. He also asked for my cancellation number