Why were both circular florescent tubes not working last night but are working this morning
Change the ballast

Especially if it hums or buzzes.   Old magnetic ballasts (heavy, transformer in them) are notorious for failing in a way which burns up bulbs prematurely.  They also flicker and are cranky in the cold.  A worn tube will be finicky about starting; what's happening is the voltage required to strike the tube increases as the tube ages, until the ballast can no longer strike the tube.

Also consider North American suppliers for the ballast, most ballasts these days are multi-voltage 100-240V and 50/60Hz, just make sure of that.  

I don't know if the T8 type bulbs exist in your country, but now is a good time to think about switching from T12 to them. T8 has the same socket as T12 so you do not need to alter the fixture (outside of changing the ballast, which you are probably doing anyway).    The ballast must match the bulb type, so select a T8 ballast.  The T12s are obsolete.