Amount billed after cancellation

Really frustrated after receiving calls from an attorney regarding a supposed amount due to Multichoice. I cancelled my DSTV 12 months ago, and as confirmed by the call centre both then and this morning my balance due was zero at the time of cancellation. Imagine my surprise getting a call from an attorney about a debt owed. Now it seems a “journal” was processed after the fact, with not enough explanation for the call centre to tell me why and for what. Ref number for my call ***8-I119.