I've just seen this!!!! I'm in utter shock and dismay.
The item is CLEARLY not as described by the seller at no point does it mention that cut nor is it visible in photos.
They surely have to back down on this one....As I stated the one time I did have a not as described experience it was swiftly resolved and refunded in full.
The only assumption I can make from this is that they suspect that you made the damage because I dont see how they can state that the item is as described or even as seen in photographs-I always ask questions about any marks or damage I see in the photo prior to pulling the trigger and in your shoes I would from those photos have assumed there was nothing especially wrong with this bag.
Its given me a really bad taste and actually has put me off of buying anything of high value or otherwise from them again.
Especially as when I sell through their concierge service they are so damn picky about everything that an unworn pair of shoes was listed only as 'Good' rather than 'very good' condition due to a tiny crease in the very stiff leather from when I'd put them on walked around my carpet decided they pinched my feet and decided to let them go.
As you state they have lost you as a customer now and probably a bunch of people like me on this forum who both buy and sell £1000's worth of items through them.
As an aside the return email you got stating that email address does not exist I've received whenever I contact them..I think its a glitch in the system.
I would contact their CEO (I dont know if you have already done this...I just read the above post and fired off this response to you because I'm so SHOCKED and ANGRY on your behalf) show them this feed if needs be.
This is awful in the extreme and I cant even imagine how furious you must be feeling..I've been planning on spending up to 6k on a bag which I would have sourced from their site..fter your experience I dont think I will.
As a seller and a buyer you pay a premium for their team to check that the item conforms to the description in every way.
They make plenty of money from us as both buyers and sellers ( as I sell through their concierge service they make a hefty % of every sale I make) they should therefore invest in staff who inspect items properly, have adequate training and dont work in a dark room wearing a blindfold as your 'authenticator/inspector' must have done to deem your bag in good condition and as described.
Sending strength and a hug I am so shocked and dismayed by this.
you WILL win and they WILL back down