I am not happy with nimble

I have settled my woolworths account and balance owing is zero. They have been calling me and insisting I owe 1k of which when I ask where the money comes from I don't get a reply. I have sent proof of payment but this has not been updated. Have been called and promised to have account updated but still no luck. They are trying to ****** money from us whereas woolworths has also send paid up letter.Please don't fall for this as they are trying to get money from hard working individuals