I was informed that the girl has disappeared and was busy causing trouble in France. Pretty sure the 'rehoming' centre has closed.
She used to work for Geoff Evans(PtoP trainer in Ludlow) so maybe he would know how to contact, or maybe just turn up there?
Its all a bit odd so maybe advice from one of the recognised centres would be of use, they may have more of an idea of whats been going on.

Yeah I've done a lot of digging today and everything I've heard points to exactly what you've written!!Nice of them to contact the owners of all their horses...she was obviously not that bothered about their futusre!!
Thanks for getting back to me so quickly..

No worries.
If I was you I would lodge a letter with Wetherbys explaining the situation, in case anything happens in the future.

We bought a horse from them last year. Serena told us she was going to New Zealand.

I think the rehoming side may have relocated to Sussex. They have a Facebook page. Hope you manage to track them down.