left no message.... collector or spam caller

Mr Richard Head called

Wish these unknown caller would quick calling my cell phone.

They contacted my "very private", very "unlisted number" and left no message.  I star 67-ed them and received an automated message......"THANK YOU FOR CALLING US BACK......IF YOU DO NOT WISH TO RECEIVE CALLS ABOUT OUR SPECIAL OFFERS.......blah, blah".....I disconnected.

Several calls per day, no msg left. They're using different numbers each time.