Landlord ? for CA Rental with util included

[Ryan G.]

I have a SFR with 2 units. There is only 1 meter for utilities at this property so utilities are included in the monthly rent. I have verbiage in the signed lease as follows:

Utilities – Reasonable utilities are included in the monthly rental fee assessed per occupancy. If it is determined

excessive utilities are being consumed by an individual or unit, management reserves the right to amend this and

hold tenant responsible for additional portion of utilities.

i. Be responsible with usage:

1. Do not leave air conditioning or heat on when no one is home.

2. Do not leave electronics/lights on when not needed.

ii. Crypto-mining is prohibited due to excessive use of electricity.

iii. Electric vehicle charging is prohibited.

I have nest thermostats installed which allows me to see usage. One unit is refusing to keep a schedule in the thermostat, thus leaving air conditioning on 1 temperature all the time. I have confirmation from one tenant that they work normal business hours and are gone most of the day (tried to schedule home owner insurance inspection and got a response via text with that info).

My question is, how can I go about enforcing them to set a thermostat schedule? Do I have legal standing to enforce it with the verbiage in the lease addendum they all signed? I will attempt to work through it with them first, but if they continue to refuse, what recourse do I have legally? Is the verbiage enough? 

Thanks.