Who do you make a complaint against a tax and revenue office to?

I live in Guam, and the place where EVERYTHING that is important gets processed or done is at tax and rev. You get your license, passport, license plate, registration, health certificate… so on so forth. EVERYTHING is done here but they are terrible! They are rude, and if you call it literally takes two days to get through. All I want to do is call to see if my husbands passport is in and I can never get through. Usually the voicemail boxes are full but the one time it wasn’t my message was never returned! Ever! So I finally figured out if you dial out to the cashier they almost always answer, so I have been doing that to have them transfer me to the passport office. The first two times the ladies didn’t care because it takes half a second for them to press four buttons. But this last lady was so ugly to me and made it this huge deal! I’m beyond frustrated with this place, but no one on this island even cares about the quality of this place. It’s just a joke to them, and most people are related to someone who works there so they don’t even have to put up with this crap. I just want my voice to be heard on the subject but I don’t even know who to go to.