The only way to stop that seller is if enough buyers check their watches on receipt and then open cases for item not as described. Too many of those, and refunds given raises red flags to eBay and that's when sanctions even bans take place.
You can if you wish inform Tag Heure's HQ of this seller's activity, I believe if they then inform eBay, eBay take action. They are based in Switzerland but I think they have their base here in the UK in Manchester, you can Google their address.
@josan179527