If you want to get in touch with the merchant, you should be able to find their contact details on the merchant’s website, for example under "Contact us" or "Support" pages. Some merchants provide contact details in their terms and conditions for escalation. Alternatively, you may try to contact them through social media.
If the merchant ignores or neglects your request, you may involve us. Please note, though, that we cannot take action on individual transactions, but we do collect information on our merchants regarding such matters.