Non payment.

I canceled my Cell C contract in September 2023 and my last payment was on the 01/10/2023. I get a further bill on November for R900+ so query this and it turns out that Cell C need to credit me R402..I am happy to receive this. On the 30/11/2023 I get a sms from Cell C stating that that the monies will be paid 3-7 days (take note that it is not stipulated that it is working days) so on the 7/11/2023 I contact Cell C asking where my money is and then they turn around and say that it is 3-7 working day so I must wait until the 13/12/2023 for my refund. So on the 13/12/2023 the money was not paid into my account, so on the 14/12/2023 I contact Cell C to find out where my refund is, only to find out that they are further billing me R544. So on the 15/12/2023 I ask Cell C to send me a statement for the R544.00 and low and be hold they can't produce one because my contract is canceled yet they can bill me.