P.F.
I own a foreign language school. We focus on ages 2-12 but occasionally work with other ages. From my experience, I think your best bet is a private tutor. Most of the programs and even classes will be pretty basic. Even the higher level classes will not be focusing in on the vocabulary you need. My suggestion would be to hook up with a tutor and do conversational tutoring so you can focus on the language you will need for your job. It will most likely end up being the quickest and most cost effective. Good Luck. P.