Originally Posted by
rupert_s
Credit card companies (in my experience) take a long time to sort these things out. Best to try and resolve with the merchant in one form or another - even if that involves head-office.
Can't speak for other issuers, but Amex suspend the charge immediately, and then usually write back in a month closing the case.
The OP has made a reasonable attempt to resolve with the merchant, without success. Chargeback is therefore fully justified, and will require much less effort, and get more attention from the merchant.