I received 6 calls in 2 days. I never answered and they didn't leave a message. But the hours they were calling were starting to really make me angry so I called the number. Initially, there's an automated "man" that tells you all representatives are busy...but within a few seconds an automated "woman" comes on and says "if you would like to have your number permanently removed from our calling list press 2".
Calling back was really bad idea.
Now you are back on square one.
They will never stop calling you, unless you stop answering the phone or calling back and block number