What a shambles. Been trying to book a Happy Mondays rate for next weekend, got the "payment status missing" error from Chrome, Firefox and Internet Explorer on my laptop. Following the comments here about Safari I then tried it on my iPhone and it went through fine!

First attempt on the phone got the "you are about to enter a booking identical to the previous one" message, ignored that and re-entered the payment info and the booking was confirmed.

I can only assume that Accor's top team of web developers have tested this on multiple platforms - Mac, iPad, and iPhone!