For me it depends on the mead (kind of like wine). If it is a super dry mead, I tend to serve at room temperature. The sweeter it is, the colder I will serve. Haven't done a sparkling mead yet but would also serve those chilled regardless of sweetness.
Did you happen to use a yeast starter? I know most of the dry wine and champagne yeasts dont usually require them but if you are fighting a stuck fermentation it may be the way to go.
One problem may be that all of the available dissolved oxygen has been consumed by the yeast and no new...