Why do I get phoned?

I've never had a contract with Altech Netstar, how and where did they get my number and why in the last two weeks have I been phone twice about a product that I'm not interested in!!!???<br> I already have tracking devices in all my vehicles on contract with another service provider.<br> I feel this is an invasion of my privacy, especially if I can't be told where I gave consent for this type of telemarketing! Surely this borders harassment?<br> PLEASE STOP PHONING ME AND REMOVE ME FROM YOUR SYSTEM, I'M NOT INTERESTED!!!!