Personally I would let it go , but GF does not let bygones etc , also do owe her , my Surly was nicked and some time later she saw it in Iceland Twickenham , so all less than 5’ of her went in and demanded it back from the bloke that said he’d bought it in good faith,she stood her ground and threatened to get the cops and informed him that the bike was reg’d ‘ all 6’ odd of him walked away !
There was a security guard in attendance so he must have thought twice about any physical stuff , There is no way I will part with money for something that is ours , hassle is something I have dealt with all my life having spent parts of my life in unsavoury environments , anyway I’ve contacted seller , from the photos it looks in good condition and there is one identifiable component that is very unique to that bike that is visible on the photo ,also was reg’d same day as mine , so I’ll go and have look if it is still up for grabs , it is actually within 6-700 meters away from Police Stn , which may be handy !