Only had that amendment case happen once.
The hotel corporate sales office cancelled the reservation and made another in its place (resulting in a change in confirmation code for reservation) and this meant the booking was not honoured by LeClub for offer/promo purposes (though accepted for points/stay purposes).
So not really an amendment. They do not really want to do on the fly amendments too often. The established way of doing it (and the one they prefer and recommend) is to call the hotel or email them and they make the booking for you. Honestly, this should be acceptable to Accor. There is absolutely no third party involved.
Technically only Reservations and sales can get involved with corporate rates. Front desk has no authority to do anything with them. Accor's policies with corporate rates are very very stringent (they do not even disclose them over the phone to top tier members).
You could have stayed 50 times in past few months on your companies rate but a *new* Accor property nearby will still not disclose that rate to you unless you email them from your corporate ID.
Accor is also not as good as other chains with assigning online booking codes to companies, so whilst we have online booking codes with Hilton, Hyatt, Starwood, Marriott, IHG and a number of smaller chains as well, we don't have one with Accor. Accor however does have very competitive rates once you manage to obtain them (only Hyatt gets close).
I've explored workarounds but they really have me stuck in a web of gotchas. The core issue here of course is their insistence that Hotel Reservations desks and call centres are not valid Accor Call Centres. If they acknowledge them as such, all problems disappear.