I'm starting to believe that all these difficulties are either subject to one being an ex FPC member, or that ex FPC members just are not willing to understand the system.

Certain, sale only, lowest priced, prepaid rates don't allow you to redeem points. PRE PAID rates. So if you have a POST PAID rate, you will always be able to redeem points upon checkout.
That process is very simple, for trained staff. You get a pin code by email once they have inserted the request, they then key in that pin, and away you go.

I may be the odd one out here, but I never have had issues with AccorHotels points credit or debit.

If the thread starter wants to try, you can contact the hotel directly and see if they are willing to offer you the rate as postpaid - not unheard of.

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