Metro PCS Privacy Policy (Possible Violation)

I had an android phone from Metro PCS, and as soon as I had gotten it, I was flooded with marketing calls from ADT and other non-cell phone related groups. According to the privacy policy, Metro has the ability to sell my information to companies that allow them to actually be a cell phone service provider (Samsung, radio tower management, and so on).

After one month of having that phone, I left Metro for AT&T, and never had any problems with telemarketers. However, two months later I saw a message on my phone stating that the SIM card had been unlocked.

So, my question is this: Can anyone explain what happened concerning the SIM card? Also, what, if any, actions can or should be taken in response to what had happened?