calls every, when i call back, phone disconnects

have had quiet a few phone calls from this number stating that they had important acct information to speak with me about, it was computer generated..It asked for me by name then asked to continue to hold while they looked up the acct. info...then said all operators were busy and would call again..I want to stop the calls but cant talk with a real person
to tell them to take our number off the list.

Calls from this number, asking for people not connected with us, called back again. its a debt collection service. When I called it back  they said they would take it off. We shall see.