Commercial Rental Laws regarding electric usage

My wife has a small daycare business in Belmont. they've been open about 3 years.

The landlords assistant called and asked if they had paid electric the past three years and they said no. They assumed it was included. It's not in the contract.

The Landlords rep asked for 7 thousand dollars for the last three years of usage.

My wife is not sure what to do nor am I.

Does anyone have knowledge of what to do or laws regarding this?

Generally they are happy with Landlord and the renewal is coming in 18 months...

Any thoughts would be appreciated. If I should post in legal forum, please let me know.