Conservice adding “adjusted” bills from March (~$450) in my move out statement tf?

This is the post vacating utility bill I received after my lease ended at Union SLU. This is for a 1B apartment with 1 person. My usual utility bill till October was about $120. For my last month (November) the utility management company Conservice had a notice saying they were under billing since June; hence I was charged over $270 to compensate.

But I was shocked to see above charges from the month of March and including sewer charges per month at about $140 when i had moved out. I haven’t received any meter readings to understand the actual calculation for the utility and I’m unsure if i should just pay the amount but I feel I’m getting overcharged. What can I do in this case? Hate this confusion this company has caused.