I'd persist and get onto ebay chat, which isn't really chat, it is typing but at least it is in real time. Ask for a supervisor if you aren't getting any satisfaction.
There is a possibility that ebay may refund you the money if they see you are right about the void to the MBG. But if they do, it will be coming out of their funds and basically, the buyer gets the machine and the money. Win, win for them!
For the future, with bigger items, insist on pick up or cancel the order of the buyer can't pick up. Every time we as sellers struck this business of people wanting couriers or problems with pick up, we ran into trouble. It isn't worth the hassle.
In hindsight, you probably would have been better off to have pointed out to the buyer that the extras were not included in the description of the ad or in the photos but as a gesture of good faith you had searched, found a couple of extras you didn't know you had and would post them free of charge. I know it goes against the grain to be nice to people who are pains but sometimes it is just easier in the long run to be done with them.
Good luck with your chat session.
