Hello,
Past month my heating system broke, it worked just on emergency for a couple of days. I called the landlord and they fixed it but I wasn't at home at the moment. Before break the switch from Aux to Emergency worked, changing the modes. This months I got the bill and it was 10 times higher than for the normal winter month. Today I've checked and both AUX and Emergency are on the switch does nothing, the landlord stated it might be like this when the temperature on thermostat is higher than 75, he changed the temperature to 70 and told me to call him when the temperature drops. The point is that I've opened the doors and dropped the temperature to 60 the AUX and Emergency were ON but the external unit didn't work and the switch still did nothing. Who could help me with a suggestion what is wrong ? I need to know who made the mistake, the landlord repairing it unproperly or myself. Thank you for your help.

Most heat pump thermostats are 2 stage. In the normal heating mode, the heat pump and blower are activated when the room temperature falls below the setpoint. System will cycle to maintain temperature. If the room temperature is more than 1.5 - 3 degrees below setpoint (varies depending on thermostat type/accuracy), the 2nd stage is activated (auxiliary heat) to supplement the heat pump and/or speed up recovery. Stages will cycle as needed to maintain room temperature. In the emergency mode, the heat pump is not used, and the system acts as a conventional electric heater. In some cases the auxiliary/emergency heat is controlled as 2 stages in the same manner as the HP and AUX are in the normal mode. In extremely cold conditions, the emergency mode is more cost-effective than the normal mode. If the system selector (on the thermostat) is set to the normal heating mode but the outdoor unit does not run, a problem still exists.

Thank you very much for your answer, but it might be a problem because before they fixed it the switch worked, I could change from AUX and blower to AUX+Emergency, but now it stays just on AUX+Emergency. Maybe I will make an experiment to equal the inside temperature with outside (23 degrees tonight), set the thermostat to 25 and check how it's working , insane but I can fight for my money if the landlord did a mistake .
I appreciate your answer and proffesionalism !

Last update,we have 23 degrees outside, the thermostat is on 70, it starts, works 5 minutes, the lights of AUX and Emergency turn ON till the temperature reaches 75, then it stops, but the outside pump still doesn't work. Thank you again, and wish you a warm night with low bills.

If you allow the indoor temperature to become that low, aren't you concerned about frozen plumbing? Heck, frozen self? If you see this potentially getting out-of-hand, start and keep a journal. The judge will be much more impressed... ;)