Keep contacting them about it, they've been known to take months to reactivate accounts, if at all. I used to deal with them a lot, terrible company.
I think this is a good site for info on what to do when you encounter problems:
http://www.paypalsucks.com/
That said, locking accounts, especially when doing transactions abroad, is fairly common I think. Even Visa have required me to do security checks quite regularly.