Do you get a little frustrated with people who give commands for you to do something, but give you no idea of how to go about doing it?

I’m with the Family Support part of Habitat. I was recently told to discuss my person’s property tax and suggest she may want to contest them if they seem high.
I said, “Well, how would we know if they are high?”
“Property owners get a valuation notice in March with tax and value data.”
I said, “Right. But how would we know if it’s high? For example, I know if my cell phone bill is too high for a month, because I have previous bills to compare it to. But how do we know if our property tax is too high?”

Nobody seems to really be able to answer that. So what the hell am I supposed to do?