Too High Power Bill with Usage of Heat?

A thermostat is noithing more than a master switch.Just one degree should turn on or off .If air flow becomes blocked thermostat will not work correctlyUnit may stay on longer than needed.Check water heater if electric a element that has burned out will cause the other to do all the work and run nonstop to keep water hot .The first sing of this will be hot water runs out too soon while in use.I would ask the repair man what he did and if anything he did could create this kind of problem.Ask hows the house being heated by strips or heatpump anything other wont run up power bill like this.