I don't know if this has really been covered before. I know there's been a bit in the lessons dealing with restuarants and such, but I've gotten a little behind on the latest episodes so sorry if this has actually been done already.
My suggestion is basically public service related phrases, but from the standing of the ones doing the serving instead of from the position of a customer? Maybe as a bonus/formal track to a regular/customer-orientated lesson.
Although it's not really part of my job, a lot of people who's first language isn't English visit my place of work (the local university has a lot of students from Asian countries in particular). Apparently, when they've got a complaint or something they'll occasionaly slip back into their first language, and not many (if any) of the staff dealing with them actually speak another language. Someone told me they were looking for people who do know more than English to help with these situations, which is why I heard about it. But I've never really had to deal with this kind of Japanese before, so I don't really know the right phrases to use (or if I'd actually understand what they say back, but that's another issue).
It would probably be useful to know for customers wanting to make a complaint as well, I guess. But anyway, that's my suggestion.