CarParts.com Forcing me to pay for their mistake Internet

I wanted a simple part (a coolant reservoir).  I gave my make & model information to Carparts.com to see if the searched-for part would fit; Carparts.com's website gave their "green checkmark" saying that it would.  I ordered.  It didn't.

Okay, mistakes happen, so time for a return, right?  After a while on the phone, they sent me "return authorization" email -- but despite my explanations and protests to the contrary (that THEY CAUSED THIS PROBLEM) they still expect me to pay return shipping, using an excessivly elaborate process, plus a restocking fee.  

I thought I had it straigtened out with the first guy, so I called again -- this time, to be rerouted to India for a garbled conversation with a person who claimed no authority to resolve the problem AND refused to forward me to management.  Stonewalled.

Look, it's not a ton of money, but that goes both ways -- it's not a ton of money for you either, Carparts.com, to operate with clarity and integrity and fix the problems you made for your own (ex-) customers.