Vodacom continue to deduct from my bank, even after contract has ended

I have two phone contracts which expired in July 2019. I was inundated by callers trying to renew/upgrade my contract when the contract was coming to an end. I advised the agents that I would not be renewing as I was emigrating and had no further need for the service. I also enquired how the account would proceed and was told that as soon as the contract term ended, the line would convert to a 'pay-as-you-go'. I now notice that I have since still been charged for several months since the contracts ended. I called the customer care centre and they advised, "oh, it doesn't convert to a p-a-y-go, they continue deducting cash and provide call time...until you advise them not to. I have now asked them to cancel these contracts and future deductions, but can't even provide written confirmation of our discussion, as they have discontinued their email service...convenient for them isn't it. I've lost about R1200 so far and don't have proof of our discussion if they fail to stop taking money...what now!!!