Im completely freaking out at this point.
Some guy calls me saying that they see an irregularity with my account and that they say that they had reason to believe i was playing an "unauthorized game". "We have a reason to believe that your system could be modded do you know anything about it?" I said that I knew nothing about what he was talking about. After that he told me, "ok, have a good night, then." and hung up. The scary part was that he knew my first and last name. After I hung up I called Microsoft Support and they told me that they would check. afterwards the representative said that everything was fine with my account and she would probably dismiss it as a prank call or hackers trying to get my info.Still she never told me that she was a 100% sure it was a prank call. She said that if they would contact me they would give me a "full reason". Im still confused at this point what the hell is going on.

At this point im inclined to believe that its a mistake. As the xbox isnt modded but the guy sounded incredibly professional, and he new my first and last name. I know the few people around me wouldnt be stupid to do a prank call either.

Its pritty easy to get some ones full name if you want to, In my youth I did a few prank phone calls.
Pritty much if you have some ones phone number you can get them name from directory. Then once you have there name you can get there home address. And do a google search of there name find out there common username. Search there username find all the sites they are on.

Find a torrent site they are on and have commented on.
Give them a ring protending to be the RIAA/MPAA and just listen to how nervous they sound when you say.

"Hello there is MR insert last name, there. I am from the RIAA and we have detected that you have been pirating insert torrent name. We would just like to confirm your address is insert address to send out a cout summons."

They then always begain to appoligise and say it was a mistake and a virus must of got on there computer and they promise they will need do it again.

You eather try hold it in and hang up on them or crack and just start laughing like hell.

Its even funnyer when you have a friend of a friend that you know pirates and sells things. Its funny how they instantly stop.

Moral of the story is make sure you get alot more proof such as getting them to give you there 0800 number to ring them back. Then check online if that 0800 number is indeed whos they say it is.

Chances are the call will probably end up on youtube...depending on how you conducted yourself during the call
Welcome to the World of Social Engineering

There not going to call about your xbox being modded anyways, "Sir, will you please stop making backups of your games" seriously thinks about it.

To the comment above I wouldn't exactly call this Social Engineering as he didn't give any information up. A professional social engineer was Kevin Mitnik though.

A true hacking legend.

Must not have been that good, he done 5 years

Watch the movie you will see how he got caught.

Edit.

He is by far a legend BTW.