Just to finish the story, after 3 ignored attempts to claim over 3 weeks I finally used the magic words and this caused the (redacted) Accor people to fix their mistake and update the points earned.
The magic words, of course, are "Credit Card Chargeback" and I recommend anyone in the same position to threaten and if necessary carry out a chargeback of part of the hotel bill, on the basis that without the points the merchant has failed to deliver the promised product.