Im very sorry you had such a bad experience, it is not nice to find out that the item you were eagerly expecting is in bad shape and then you have to do a lot of paperwork to get it returned and refunded.I've got a similar real bad experience with Vestiaire Collective. Bag with scratches and very troublesome return process. Never buying again there.
I have to admit that for me, the experience selling and buying has been so far more positive, although with some bumps.
I recently bought a Fendi baguette in very good condition, which passed with flying colors the authentication and verification process. When the bag arrived I couldn’t believe my eyes: it was stained in many parts, scratches on the patent closure, worn out spots in the fabric of the body, and above all, dirty as hell...in no way or universe this bag could be considered in “Very Good Condition”.
Immediately I reported the issue, with so many details and pictures of most defects. I cleared stated their own terms and conditions for the sale and their own classification of the item conditions. In less than 24 hours they invited me to return the bag for a second inspection and on the next day they confirmed my claim and reimbursed the money. This is the second time I had to reach out for a non compliant item, and in both cases they were diligent.
Nevertheless, this experience also shows that their authentication process is far from perfect, so never hesitate to open a complain, especially if you can recite back their own regulations, showing them proof that those were not listed/ visible in the description or not in accordance with their own classification.
Additionally, take the advise given above on preferring payments via Paypal so you have a back up alternative to solve the dispute.