I know the bank I work for would refer you to Paypal first to resolve, then if you have no joy there the bank investigates. Horrible thing to have happen, especially that sort of amount I hope it's all sorted nice and quickly for you.

ETA- it sounds like you have done all you can for now (changed passwords, reported to Paypal). There really isn't anything more you can do aside from wait for Paypal to complete their investigation, unless your bank says otherwise (I can only speak to what we would say at the bank I work at).