To wonder what the fuck I'm going to do now!

[SharkiraSharkira]

I bought a motorbike a few months ago and a while ago it broke down. After some closer inspection and assessment by qualified persons, it's basically fucked and I'm now in negotiations with the sellers to take it back and either repair it or refund me. For various reasons this is looking like it will be a long time in the making so I have to basically write off that money and bike for the time being.

That leaves me with a big dilemma.

They sold you a dangerous vehicle with a fake MOT. Make sure they know that you know that. Give them 48 hours to give you a full refund or replace the bike or you will ensure they lose their MOT license and their ebay shop. Get your 'expert' to call them and lay it on thick about risking a young woman's life!
I did that once, a shaken looking garage proprietor handed me a replacement car and assured me that he had sacked his MOT tester. Issuing a fake MOT is something the police take quite seriously, so you might want to (threaten to) deliver the bike and MOT to the local police station.

Can you make a claim via ebay?