Ebay do not get involved in claims like this.
Their Money Back Guarantee allows you to return faulty items but not to claim for damages.
I would advise you to seek legal advice - try and get a free consulatation via Citizens Advice or another method - and see if you have any legal redress against an overseas seller.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)