Lawyers keep calling me for a debt iv settled

MBD has been calling me day in day out for an account I settled last year already! When I call Virgin active to get these people to stop calling me they tell me I dont owe anything and I should inform MBD to stop calling.. when I relay the message to MBD they tell me to call Virgin active ??this is annoying and unproffessional! I will not tolerate being harassed for a debt i settled over a year ago!!!