Unbelievably having provided all the receipts, all the emails, a detailed explanation and asked them to check with both hotels back comes a email which reads:
(...)
This time a general rejection without precisely specifying the reason for the rejection so I can further challenge their issue. Although the implication seems to be this is a multiple stay and misuse of the card. Which it isn't.
I've emailed Customer Service yet again.
Something tells me they don't really want their Platinum members business.
Sorry to say this is nothing new; In my experience this is standard practice with Accor CS; Issue keeps going back and forth expecting the customer to give up or forget.
I bolded the main action on your comment; Keep the issue on the table, providing accurate info and requesting a solution within the T&C. Eventually contact their CS by phone, ask for a Supervisor and find out in a few minutes if you trust him/her to be the right person to sponsor your case within Accor.