I think I would pay. Pay for the cheapest upgrade
and you might get a better one, although the bungalows are all the same
anyway, it's just the view/location.
I wouldn't stay in the garden room in this hotel, no way.
It's better to go to Le Moana.
But Thalasso is way nicer and newer, just got some renovation done.
It's a spectacular hotel/location, don't let the silly rules ruin
your experience. If you got stuck in the garden bungalow,
it would be quite horrible, like staying in a laundry room
instead of XVIth century room in a grand Paris hotel...