Phone Calls about Cars Warrantys

Is your cars warranty about to expire, that is the message on the other end and they want you to extend your cars warranty on the phone and they continue to call day and night on the cell phone and on the home phone. First of all I bought two used vehicles and I did not want to buy an extended warranty and get scammed from the start. When I bought a new car it was hard enough to get coverage so you want me to extend my warranty and pay you over $700.00 for nothing.
90% of these folks are scam artist and give you nothing for your money so do your homework and research the company before you get into any kind of contract. Do a google search of the phone number that calls your cell before you answer if you are unsure of the number and you will see alot of people got the same deal or scam. Did they call you about your warranty?