Sent to collection after cancelling service 2 plus years back

If i could give them minus 1 i would. I use to be a loyal customer 2 or so years back. I got fibre and cancelled. They said it was successfully cancelled. Then recently i started receiving calls from Eastern berry collections. They say i owe rain money. I log in and see my account says i owe. I paid it not to deal with this issue and cancelled online yet i didnt owe anything . I phoned and asked am i now cancelled. They confirmed yes i am. Just now i get a call again from Eastern berry collections. I log in again to the website i see i owe again. I like to be clear my usage is 0 for 2 plus years. It was cancelled then and now yet im still having this issue. Would you trust a company like this when there is so much headache just to cancel. Now after 2 plus years i must pay close to R400 for 0 usage just to cancel