I would have thought that ending up in the Mercure, any Mercure, was a downgrade, nothing else. I have yet to have a decent stay in a Mercure, although I am told that there is a family run one in Zurich that is really good.
I tell a lie, I did have one good stay in a Mercure last year, in Bridgewater, England. It's located on the main A38 through town and is new (that helps) and pretty decent.