Trouble cancelling contract

I took out 2 contracts on vodacom that went off with 1 debit order. When the contract was coming to an end, I called the call center to cancel, who said I should call back in 2weeks. I called back, had a lengthy conversation with vodacom, then 2 weeks later R87 went off my account, I called vodacom and they assured me it was cancelled, but then another debit went off, and an agent called me telling me I am due for an upgrade, when I told him I cancelled the contract, he referred me to cancellations. Yesterday a lady called me again, saying I am due for an upgrade, when I asked her why is my contract not cancelled, she said oh, I see it is cancelled and your account is at our legal department. Seriously? Legal, I tried to call vodacom this morning because I received a statement, which I cannot open, and I have let vodacom know but they have never bothered to send me a statement in a format that can be opened. Can somebody please tell me why contracts are not automatically cancelled firstly because I signed a contract for 24 months and not longer, and secondly, why is my account, that was cancelled at pre legal? I don't have any details of this.