Lets say you worked at sears with the tv's.You take the tv home and it doesnt work.Do you call sony and tell them to replace or do you return it to sears?
LOL, I know this isn't the answer you're expecting, but technically you're supposed to call the manufacturer.
A lot of items you buy nowadays(to be fair, mostly electronics), you will notice a piece of paper inside the box that says "STOP! Do not return to retailer if there is a problem. Please contact us directly at 1-800-blah blah." I just bought a Brother laser multifunction with the exact same note and I remember the higher-ups at the company I worked for specifically telling us not to deal with Rock Band hardware and let Harmonix deal with issues directly.
Of course the customer is still most likely going to bring it back to the store and the store usually has no problems with it.
Just a random example that sometimes contacting the manufacturer directly is the best way:
I had a customer who wanted a laptop fixed. It had been a few months since they bought it and of course the store couldn't exchange it for them - we didn't even stock the same model anymore. I told them they have a warranty through the manufacturer whom they should contact. The customer demanded that the store resolve the issue since the product was purchased from the store, not the manufacturer.
I contacted the company and they said they will send everything the customer would need to send the laptop back, directly to the customer. The customer then appears a couple days later saying the manufacturer sent them all this stuff, but it wasn't their responsibility to pack it all up and send it off and they shouldn't have to pay for the shipping. I agree to send it out on their behalf and pay for any shipping fees.
When I opened up the box, there were packing material, pre-paid shipping labels to and back from the manufacturer, and even two pieces of pre-cut tape to seal it all up. I send it away and received it back in a few days. I called the customer to let them know the laptop had returned, and the customer told me she'd be by in a couple days because she lives out of town and it takes a while to drive back.
This woman would have saved herself days in waiting period and a lot of gas if she was willing to accept the most efficient course of action.
I contacted Spyderco for a clip because I thought it was the most efficient course of action to make all parties involved in this situation satisfied.