Game center being linked to different accounts

I have deleted my iOS app a couple of times today and reinstalled it. Each time I subsequently start it up I get a screen saying another account is linked to game center. Which one do you want to keep. It gives my team as one option and a team I've never heard of as a second option.

It has done this both times with a different second team each time.

I have also had someone accessing my account doing 4 hour training sessions and auto assigning training points, and deleting my strategies and putting a crap strategy in it's place under a different name.
May i recommend you change your password and i would also say NEVER give out your log details to anyone!

I terms of the "what account do you wish to keep" this is normal as you have clearly linked your accout (a good thing) it is just ensuring you are connected to the right account, if you wish to re-start then go for the one that isnt linked and re-link it.

I hope this helps!
I have never given out my password. I don't even remember setting up a password for the game as I played it on the iPhone app. Given that my team is one of the top hundred ranking teams why would I wish to restart.
http://i.imgur.com/iMmUTJg.jpg
http://i.imgur.com/6qixyDd.jpg