When purchasing new laptops and similar equipment, I've often seen the MAC address printed on the outside of the box and used as a unique device identifier (e.g., for inventory tracking), so there's a very good chance that at least the retailer the equipment was purchased from would have a record of it. I wouldn't be at all surprised if the manufacturer also knows what warehouse that device was shipped to and the warehouse has a record of which retailer they sent it to. As others have already said, though, none of those records will do you a bit of good without a court order demanding their release.
Another point is that MAC addresses, as a general rule (such as in IPv4, but not in IPv6), do not survive past the first router they encounter, after which the next hop is made using the router's MAC address. You didn't specify whether the person you're complaining about is trying to break in over a wireless connection or over the wired connection to your ISP, but, if it's the latter, you're seeing the MAC for your ISP's router, not the attacker's computer.