Dude that sucks balls. I had the SAME thing happen to me only it was for $2000. They claimed that I had abandoned my apt 2 months before the lease was up and was resposible for the rent and late fees and penalties. Needless to say it took 2 years of bitching to get that sorted but in the meantime still had a hit on my credit. While you are at this make sure they report to the credit agancy their mistake and find out which company they report to because they may mark it paid in theier books but not fix the damage they did to yoru credit and you will have a mark of something going ot collections for howver long till it ages out, Good luck with that though, I wish you the best.