UNFAIR BILLING

I had a contract with Vodacom from 2022 to 2024. I settled my account in January 2024. I received 00 statement from then until now when the statement suddenly says I owe R2500+!!! I phoned them and they told me that I never canceled my contract but as far as I remember I did! I even requested for those numbers to be blocked because I no longer use them!! The question is who gave them permission to unblock them?? Why am I receiving a statement after the whole 20 months???? I am so ****ed this!!! Am i a cash ***?? The unfortunate part is that I do not have a reference number of the call that took place over 20months ago!!!!