I'm afraid that I don't think TNT will do anything about this (although of course I may be wrong). Basically, if you choose to trust someone with an object, then you have to be prepared that you won't get it back - sad but true. On the other hand TNT are notoriously slow at getting back to you, so you may just have to be prepared for a long wait. If they do actually take action, you may not be able to get the object back either, because chances are she's sold it on, and it already belongs to someone else who didn't realise how she got it in the first place.
This is all just what my gut instinct is on the matter, and I expect someone on this board will know more about situations like this thatn me. A basic rule on Neopets is to just use your common sense - unfortunately there are plenty of people out there who want to get whatever they can from you, so you have to be very cautious.
edit: if you look at
http://www.neopets.com/security.phtml, on number 4 they specifically advise against doing this. As they say to report this, hopefully you can at least get the user frozen.
Neopets name:
msmanicx - Premie and proud
August 10th 2007 - the day that I get married to
klanluke