Unlocking iPhone 5 for MetroPCS, not sure if scammed via MetroPCS customer service representative?

I bought an AT&T iPhone 5 from a person who was selling it for his girlfriend. I've been trying to unlock it to use on my carrier, MetroPCS network. I heard you could unlock it via your carrier or AT&T if I had an account with them (which I didn't cause I bought it off someone). I called customer service off this number (1 888 863-8768) found a website to get a direct line and I got this girl, who asked me for the name on my account, my name, the account number or the security "code" because I didn't have it (it's my mother's account). I told them some of the info but I'm sketched out now because it didn't feel right after the representative told me I could go to this website to unlock it: releasemycode.com. I went to it to check it out and was instantly sketched from it. Can MetroPCS customer service representatives unlock phones over the phone? Can MetroPCS unlock my AT&T iPhone 5?

Only AT&T can unlock this iPhone. You'll have to use AT&T prepaid for 6 months before unlocking it.

Prepaid / GoPhones: Device has been active for at least 6 months