(edit title) Recent CSN hacking and re-billing of paid accounts What do/should we do? Options

[qetesh71]

I am a former Swedish citizen, now married to an American and am an American citizen myself for several years.
In July 2006 we paid off a student loan from CSN and received a faxed letter stating the account was closed, on a CSN letterhead.
This week (Feb-2013), we've received 2 bills from CSN and 1 bill from Svea Inkasso.
We called CSN on Monday 2/18/2013 and were advised that CSN’s network was “trespassed into” and it opened up closed/paid accounts, including mine.
The 1st CSN agent we spoke to quickly confirmed that she could see that our account was indeed open and that she could see that we had paid it off.
On Thursday, 2/21/2013, after receiving the 2nd CSN bill and the Svea bill we called CSN again.
This time the 2nd agent while confirming what the 1st agent had told us about the “trespass” and the closed/paid accounts, hesitated to confirm that our account had indeed been paid off. She seemed to be trying to indicate that we had owed more money at the time we paid the account in full, in 2006 plus late fees. Basically we suspect that CSN is attempting to reopen our paid account to get more money from us.
Did anyone else hear about the “trespass or hacking” of CSN’s computers, and does anyone have any suggestions for us on how to resolve this issue?