Very High Utility Bill - What can I do?

Hi, I'm renting an apartment for the first time. I share a 2bed/2bath with a roommate. I got my first bill for utilities and it's nearly 500 dollars. This seems unusually high to me - I spoke to my parents and they pay less for utilities in their house which is more than twice the size of the apartment. It can't have been a heating bill - I live in Southern California and it hasn't been particularly cold.

I live in an older building and when I brought this up to the leasing office, they told us that gas, electricity, HVAC, etc are not individually metered and that it was a shared amount broken down based on unit size and occupancy. There's only two of us and we're pretty conservative with our use of utilities - HVAC alone is over 200 dollars and we haven't used it all month.

They use a service called "Conservice" to charge out for utilities. From a quick look on reddit it seems like a lot of people have issues with them. I'm feeling frustrated and stupid; I don't know what to do about a bill this high. Is there any action I can take?