I work in the industry, and trust me, when i say that they are really annoyed by this kind of request

they have plenty to do everyday

when they received such emails, they only forward them to someone else, like reservation or reception

unless it is a major complain, he will not waste his time with this


as i advise you, just email the hotel generic email or reception mentioning that you're a card member and you would like to be upgraded upon availability