double debited

I had a contract with cell c which came into an end in august 2021, one lady from cell c called me offer me an upgrade which I agreed on, she advised me that I will pay 250 effective from September 1st and I will pay on my debit order date which is the 26th..no one told me that once your contract comes to an end you call in to cancel I was only told of that when I called in to enquire on the R520.86 debited on my account, ref *** the lady explained to me that the debit includes a sim swap which I did and the month to month contract that I did not cancel on the phone contract which I understood as much as I was never told that I have to cancel contract even though our contract and agreement has come into an end. The lady also mentioned that I was charged an amount of approximately two hundred and something for a pro rate data which was loaded when I agreed on the upgrade on the 20th of august, now my argument is that when I was given an offer to upgrade I was told I was only going to start paying for my data R250 in September the lady never told me I was going to pay for pro rate an amount of two hundred and something, in this case I was misled and the sales person did not disclose all the information she was meant to disclose in order for me to make an informed decision, if she had told me about this pro rate fee I was never going to sign up for an upgrade. I need this matter to be looked at, if Cell C cannot refund me back I would like to lay a formal complaint requesting for a transcript and cancel this contract with immediate effect