A positive story for once.
I had a one night stay at the Marriott CDG airport booked. When I arrived I mentioned that I had used the online check-in so they should have my details. At that point the check-in assistant mentioned that they had some internet issues which meant they didn't have my check-in details. After a few more exchanges of general chit-chat about how you can't trust Marriott IT, it became clear that they had a general internet outage, street side. Which meant there was no guest internet either.
At this point I posed the friendly question if I could cancel my booking without penalty [I was past the deadline] as I could make another booking at another nearby Marriott property. My check-in assistant was fairly stressed and quite possibly short on experience and didn't know if that was possible, but she checked with the duty manager without being asked to [plus points for that]. The duty manager, a lady called Fatima, immediately understood what I wanted and where I was coming from. Indeed the airport Courtyard had been providing IT services from them all afternoon. She called over and asked them to transfer my booking from the Marriott to the Courtyard, which they were happy to do. Two minutes later my app updated on my phone with the changed booking details.
I set off to the Courtyard were I was greeted by their duty manager who explained they were happy to help and had been able to provide a room upgrade also.
So far, so good. No late cancellation penalties as the booking number didn't change. Points have been posted. The only downside is that arrival points at Courtyard are 500 and not the 1000 of the Marriott. All in all, it seems a positive customer service experience. Well done Marriott, and particularly Fatima.