Thanks.

Wow so they can literally choose not to return an item and get still get a full refund. My only way to request a return is to challenge the dispute which I'll most likely lose because they usually favour the buyer? Ridiculous.. I mean I only have photos of the boxed item, so I'm probably not going to get anywhere by challenging it.

Well this really puts me off selling anything on eBay to be honest, though for me I think this is the first time it has happened. I have until the 10th to respond to the dispute. Looks like I've lost the item which can probably be easily be sorted with a cheap battery and thrown away over £100 on top of it. Might as well have just thrown my money out the window.