Merchants very very rarely win chargebacks. They can represent all they want with proper documentation, and they may even win the first chargeback, but that win can easily be reversed by the credit card company, if the customer is persistent enough, with no explanation to the merchant. I know this because I've worked in credit card processing.

So any time you run into an issue with a merchant, if they look like they are acting in bad faith, you should just chargeback and stop wasting your time.