can pokerstars sue me...?

[kuldipc]

ok i got an email 2 days ago saying pokerstars have overpaid my account by $3000.
This happend in february and i having not checked my bank statement for along time in those 2 months have spent the money that overpaid me on various things such as going out with friends things i do on a weekly basis.
Thinking im paying with my own money which i get paid frmo work and little extra from poker and having received the email they want the moeny back i however checkin my statement. Like i said no longer have this moeny and cannot afford to pay them back i am auniversity student and money is smoethin i can get hold of what procedures can they place on me to get there money back at the end of the day i see it as they made the mistake it was there error and i having not known till 2 days ago was not in the wrnog thinking.
I am spending my own money i feel so sick and scared and im 20 years old and do not have the money they want i never asked for any over payments or to be put in this scenario what you guys think will happen to me and what can i do i mena theres no way i can pay back i dont work i get my money from government grants i live in the united kingdom i joined the site thinking there procedures with the amount of money comin in and out of there business would all be carried in a safe and responsible manner.
I am know very scared at waht they are planning to do i would have never joined the site if i knew they had these flaws and can make such big stupid mistakes please help guys.