Harassment by sales people

I had an account with home choice which I paid off more than a year ago. Since then I never rested from their call center personnel, they call every day at least 3 times a day selling bedding to me which I have been refusing for the past year. Been telling them to remove my number or name from their database or books whatever they are using. This is so annoying it feels like I owe them something and what irritates more is the more than one call a day. I am at a point of just screaming on the phone when they call but I don't think that will stop. Please help.