I suspect that there might be a slight language miscommunication.

Just a guess, but I think they might mean that they will not guarantee an upgrade and if you would like to lock in an upgrade it is possible as a cash upgrade. This is well within the WoH T&C.

Nevertheless, this is a departure from their policy in the past (the management level staff has changed and I noticed many economies on our last stay in May of this year).

At the moment, I think I would request a "clarification", and see if you can get anyone better. Other than that, I would demand the upgrade if it was showing online for the entire length of your stay. Unfortunately, properties can be very stubborn and stingy regarding such upgrades.

Good luck