I didn't have any trouble at all with Shopbop. My order consisted of 2 items that were sent free. Both had to be sent back - one for a refund, the other for an exchange. I did have to pay to send them back. I felt that my refund was processed very quickly and my received my exchange fast. Here is their return info from their site...
How do I make a return or exchange?Simply follow the instructions on the invoice included with your package. Securely pack and seal the return merchandise and invoice in an appropriate shipping box or envelope, and send back to us using an insured service to the above address. (This will provide you with recourse on your package, as we cannot accept responsibility for packages that we do not ship ourselves).
One time I bought some jeans but one of the rivets were missing I returned it to them and they were so nice about it. They sent me a coupon for I think it was somewhere around 10-20% I don't remember off for my next purchase.
I also made a return because the bag had some issues with it. I called to let them know and they emailed me a return ups so I didn't have to pay. They also processsed the return quickly. Pleasure to do business with.
I've returned many things, never any problems. The only thing that sucks is that you pay for the shipping, it seems almost standard nowaways to not pay for return shipping so it's annoying. Otherwise great though!