Sorry I was sleeping (i'm in GMT+1)
I think establishing a case on eBay would be enough. they almost always side with the buyer. Also if there is an authorized Chloe reseller (a Chloe boutique would be the best) near to where you live I would advise to first go ask about this bag. that's what I would do.
As for the authenticity I would rather not speak about it as I only owned three genuine Chloes to date. it's the Rue la la bit that struck me.
it looks ok but I would really go ask a SA at Chloe.
Why not use Authenticate4u service? It costs £5! They will assess the authenticity based on photos and will issue you with certificate. eBay and PayPal honour their assessment.
I'd personally not rely on SAs, I've heard cases when mulberry staff assessed bags incorrectly.
Thanks girls I will assess the bag when I get it. I have other Chloe products (not bags) so I will try to determine first what I think and go from there.