I have received two calls from them, and I never pick up because I don't know them. Then when I try to call back, it says the number was disconnected. That's what alerted me into googling the number, and finding this webpage.
I know that you cannot insist that they never call you again, because it is an outsourced service that does not need to follow the guidelines of an American company. I've just chosen to put it on my phone's "block calls" list to HOPEFULLY get them to perceive it as a no longer valid number, and take it off the list they obviously sell to other sleazy companies.

we put several numbers like this on my sisters blocked list after a year when she ran out of room to block any more she took a few off the list and they was still calling her daily. so it would seem once your on this list you are there forever