I've sold and bought a lot of stuff on Ebay including selling multiple Mac laptops. This situation besides being traumatic to the seller (or buyer depending on the situation) is very interesting as to how ebay will address it?
This was several years ago, but I have a friend who purchased a computer on ebay advertised with a specific graphic card. In reality the computer did not have the card that was advertised, but for some reason in the dispute, ebay sided with the seller saying the differences were not enough to warrant a return despite the card having 124MB VRAM instead of the advertised 256MB VRAM.
Despite my story above, what has bothered me about Ebay is that it has taken steps to be friendlier to buyers at the expense of sellers. For example, instead of allowing the seller to dictate the buyer pays for insurance as a term of the sale, Ebay has taken this away this choice from the seller.
If you have a piece of computer hardware, and you know what the serial number is, and you mail it off, what exactly prevents the buyer from switching computers and saying "you did not send me what you advertised" and asks for a refund? For this situation Ebay will have to develop a verifiable process because someone is being scammed.
The reverse is the seller lies about the computer and sends something other than what was advertised.
I want to know how the heck Ebay can determine who is telling the truth?
The worst thing about being the seller is that once your computer is in the buyer's hands, you no longer have any control over your computer. For the OP, at this point, I don't think there is anything you can do but contact ebay and discuss it with them. Someone else has your computer. Hopefully you documented what you sent. If so then the buyer is a crook. Hopefully you took several pictures to distinguish between what you sent and what the buyer says he got.
But does everyone see the dilemma? How does any 3rd party know what you really sent the buyer? This is going to make me do some research because I will be selling a laptop in the near future on ebay, that is if I can satisfy there is a means to verify what exactly has been mailed?
Helpfull links anyone?