This question has been asked a few times in this thread and the answer is always that you should just pick up the phone and call if you wish to speak to the concierge.

Meanwhile I am here at the hotel, which is packed full, enjoying an upgrade to a very nicely renovated junior suite.

Earlier I was at a Marriott Luxury Collection property here in Paris, which was also full. But even as a Marriott Lifetime Titanium member there was no upgrade for me. It is just not the Marriott way.