After 16.5 year of being an contract client,

I cancel My contract 17.12.2019 (which was on an month to month at that time) and the end on this contract will be on the 17.01.2020. So I ask the lady which have I spoken too, when will my last installment be and she replay at the end of December 2019. Further I ask her, will I still get my complete contract benefits, she replay yes. On the 14.01.2020 I got an SMS to state my next installment will be on the 28.01.2020. I Call Cell C, and ask them why and lady said, because of 2 x reasons 1 is because I got my package benefits and the second reason was, because when I upgrade the last time 2017, I was 1 x month behind in payment, she said they give me airtime and then I pay. I told here what the other lady said and that she must go back the phone recording and she said the whole time I got my benefits and I was 1 x month behind. I also said I'm going to stop the debit-order and will not pay. After that, she said I must call accounts I stop the debit order, but on the 28.01.2020 it go of. I went to my Bank to find out why, they told me Cell C use and difference reference number, that is why it went off again. So they are ...........