Spam Calling from "OnStar"

[SmrtGuy04]

I constantly get spammers calling me indicating that they are from "OnStar" and they will gladly give me a free month if I only confirm my PIN. 

I consistently say no, I'm not giving my PIN on the phone to someone who cold called me. If they can give me free month, I'm sure they can do so without having my PIN. 

If this is legitimate, why does OnStar need my PIN? The whole point of a PIN is that only I know it. 

If this is not legitimate, can't GM do anything to prevent this? 

[Advisor_Makayla]

To Opt In/Out of marketing communications, we recommend that you visit https://www.gmcontactpreferences.com/ and update your contact preferences. If this doesn't work for you, please push the blue OnStar button in your vehicle or call 1-(888)-4ONSTAR (1-888-466-7827) to speak with a live Advisor and they will be in the best position to assist with Opting out of OnStar communications.