Incorrect Billing

Good Day

In July 2021 my property lease agreement expired and I moved to a new property where Clear Access Fiber was not compatible in that area, hence I had to cancel my contract with them.

I received a settlement letter, paid and sent proof of payment. To my surprise from October I have been getting calls their legal team saying that I still owe them money. Why was I not informed of this a year ago, why is it coming back with interest?

When I query this no one is able to explain to me the statement/invoice that they are billing me for and/or amount