Location: In the old port - you can easily walk from downtown. If you want to use transit, I would say that Place d'Armes is the closest subway.
Service: I received amazing service from Susan, who seems to be the go-to person at Universal. I exchanged a few emails with her to confirm the rate of Turkish Liras, then was able to reserve the amount that I wanted for pick-up on a specific day. It was quick and painless. When I arrived on-site, the money had been set aside for me and Susan gave me the best possible rate (i.e. the rate she had shared with me in our initial email exchanges).
Universal offers pretty competitive rates that you can check by either giving them a call or sending a quick email. Susan & team are very quick to respond to queries. I plan to use them again for my text trip.