Where on half.com do I file a complaint against a seller?

[yllus]

Now that half.com has become half.ebay.com it seems virtually impossible to find a link to file a complaint about a seller. My cousin bought a textbook from a seller and it's been five days since the transaction...no "Report Problem" button has appeared. Is there any URL or number she can contact to find out what's going on?

 

[dude8604]

http://half.ebay.com/help/index.cfm?helpsection=buyerorderprob#5