I hate to break it to you but these are unreliable cars. (i dont know the answer though), next time, dont get a vauxhall!!
Your problem very well could be the hazard switch. i have a 1994 honda civic too i found whenever i disconnected the hazard switch from the wiring harness my turn signals brake lights and of course hazards do not work. Maybe replace the hazard switch..
You could have a blowen fuse or a faulty connection!
it could be a bad relay
The light control module could be the cause of hazard lights coming on after the car is turned off. There could be a problem that has caused this module to become wet and it is now not working correctly.
Bad hazard switch.
Check the bulbs. If these are OK it could be the switch on the brake pedal arm.
It could be a faulty ground wire.
did you check your fuses
Check the fuses and it may be the flasher relay as they have 2 try turning the hazard lights on and off a few time as you relay may be stuck.
If your hazard lights don't work but your turn signals do work it could be that your Hazard Lamp Flasher needs to be replaced. Your car has both a "hazard lamp flasher" and a "turn signal lamp flasher". Your "turn signal lamp flasher" is working but your "Hazard Lamp Flasher" may not be working. Buy a new "hazard lamp flasher" and install it. The hazard lamp flasher is located behind the instrument panel to the left of the steering column.
I had a similar problem with my 1991 Maxima. The dashboard lights did not work. I could not find a fuse. Then I noticed the parking lights did not work. I could not find a fuse. Finally I noticed the tail lights did not work. I checked the fuse and it was burnt. After replacing it all is okay again.
There are a variety of reasons the hazards lights may not work. The flasher module could need replacing. The fuse may be blown. The bulb may be blown. There could even be an electrical malfunction.