What are my options for investigating a sudden doubling in my water+trash+sewage bill?

I rent an apartment in Los Angeles in a complex with >50 units. We pay water+trash+sewage separately from our rent, and it's not through DWP, it's billed through RealPage Utility Management. Our usage isn't metered per apartment so I think the entire building's usage is split between all the residents. Our June and July bills were both around $80-90/month but in August it jumped to like $160/month, and the Trash component is more than double. I don't think it's likely that the building disposed of >2x the amount of trash in August as in June/July. What can I do to investigate this?

I've already tried:

• Calling RealPage: they said ask your property management company about this
• Calling the property management company: they only pick up the phones 1 out of every 10 attempts, and when they did they said to email them with a copy of the bill and they'll investigate, and then they never replied to me

What I'm wondering is, is there some legal right that I have to a breakdown of this bill, through the city/county/state or something? Do I at least have the right to see how the bill is calculated, ie the total usage and the rate and stuff like that?