did not answer when I picked up phone

I received multiple calls from this number yesterday. When I answered, a man said that I had made an order from my MasterCard and that he was sending me a $120 gas rebate. He used my first name and asked me if I was between the ages of 18 and 80. He abruptly hung up as I was asking about the product that he claimed, "I had ordered." DOES THIS COMPANY HAVE ACCESS TO MY ACCOUNT? I am monitoring my account,but has anybody any money withdrawn or orders placed on your card without consent??? Thank you!

calls and leaves message, using my first name called again two days later and talked to me using my first name, laughing hangs up

Has called me six times in past six hours, starting at 5:12am. I tried calling back, but got same recording that the phone number was no longer in service. I will be calling both Verizon, and ATT who is my cell provider to find out what they can do.

Spoke with their annoying collections agents, in an attempt to stop this harassing calls, to no avail. They continue to call relentlessly, at all hors of the day/eve. 6x just today. This is an elderly couples residence, who have absolutely no debts!

They called 5 days during the past week. I called back to an auto prompt to have my number placed on a "do not call" list. I think I just confirmed for them that mine is a working number. Can these people be stopped ? Underdog ?