I was clicking through the accor sites and see that they have updated the BPG site:
http://www.accorhotels.com/gb/garantie/formulaire.shtml
It now allows you to upload a screenshot (or any other file) which will avoid any future "I saw / you saw" conversation. Actually to be more precise: You MUST upload a screenshot - without which you cant submit the request.
What seems slightly tedious is that you also need to upload a screenshot of your actual Accor reservation instead of just giving them your confirmation number.
What I see as odd is that excluded are for example Accor Advantage Plus Rates....If you find a rate lower than the AAP Rate wouldnt that be in any case a really low rate? Anyway..
Other issues:
1) "The room category claimed for must be available and bookable on another website at the time of verification by the Accor customer service department." So if the hotel has a single Presidential Suite and I can find it cheaper somewhere else but I have made a booking at Accor already and hence not-bookable (meaning I cant re-book the only room available), I cant make a claim?
2) "The exchange rate used will be the Accor exchange rate in effect on Accor Internet sites at the time of the initial reservation."... and how would I know what that exchange rate is?
..and then: "Accor reserves the right to refuse a claim, if the exchange rates used by both websites are different. Differences in the currency exchange rates are excluded from the offer."
3) In the whole "conditions" page it does not say within what time frame Accor needs to get back to you.