Unfortunately, for you, I agree with the others, that you're out of luck.
I have a small apartment that I rent out, and due to factors of certain tenants unable to get service due to bad credit, and high turnover, from time to time, I've included the electric in the base rent.
If too high a usage is a problem, WRITE IN a CAP, such as LL will include monthly electric up to $50.00, or whatever amount you wish to cover with the rent.
I have the option of charging them the EXACT amount based on meter readings too, but I have to make sure I BILL them immediately when I get the bill, and collect it in a check separte from the rent, and often, I've not been up to date on this, and have not collected, and lost money.
Average monthly electric bills for that apartment had ranged from $50.00 to $200.00. The lower bill is from a retired gentlemen who often stays with his neice, and the higher one is a tenant using it to run a consultant service, and leaves the several AC's on even when he's not in.
Next time, see if you can bill them based on the exact usage, or have the utility bill them direct.

