The problem is that there is only one thermostat located in the upper unit.

You can set up stuff to help you manage remotely while you are there such as wireless door locks, ring camera, wifi thermostats, etc..  

Your talking about purchasing all new baseboard units, having them installed, all new electrical wiring run and either a central thermostat or room based thermostats.Regarding your existing furnace, did you only get a parts replacement quote from the one contractor?

On site Wifi controlled or preconfigured keycode devices for thermostats, door locks and the like make management remotely a breeze. 

Reading the story, I'd say what sunk him was changing the locks, removing the thermostat, and removing the mailbox.

Some of these devices includes smart fuses, dimmers, locks, sensors, curtains, and thermostats. 

Unit 1 has the thermostat that controls the gas heat for unit 1 and just the first floor of unit 2. 

Electricity heats the igniter plate. then there's the small matter of electricity to signal the furnace from the thermostat.

Landlordstat thermostats...

We told him someone was on his way to check it out, the thermostat was damaged, but I told him we need the apartment to renovate.