Circuit Ciity charging a 15% fee for returning a defective gateway notebook

I purchased a new gateway laptop that was defective out of the box. After hours on the phone with Gateway they said return it where it was purchased for another unit. Circuit city does not have this model instock any more and wants to charge me a 15% fee since it was opened!!!!!! How can they charge me $125.00 fee for returning a defective product they no longer stock----- What a scam!!!!!! After hours on the phone that say that is policy.