******! Cell C denying receipt of funds paid to them to delay cancellation

Due to poor service delivery (multiple dropped calls, slow internet speeds) I decided to cancel my Cell C contract early. I was advised that there was an amount that needs to be paid in order for the contract to be cancelled. I paid this amount on the 8th of November. More than a week later Cell C is claiming that they have not received the funds. I have provided them with proof of payment and the payment has still not been allocated to my account. As a result I am unable to proceed with the cancellation of my contract. I am starting to suspect that they are deliberately delaying the allocation of my payment so that I can not cancel my contract. This is shameful and *********. Resolve this ASAP!!!