VW Polo

If you have spark and suficient fuel pressure, it is time to test for pulse at the injectors. Get a "noid" or small light to plug into thte injector plug. It should blink when the engine cranks.

I take it the check engine light did not come on. Also, the Polo is European model so maybe a barrier is the meaning of words. You say "fire". Does that mean start and run, as in the car will not start or run OR are you saying that there is no spark at the plugs?

If you have spark at the plugs and fuel is being delivered through the injectors to the cylinders it is technically a timing issue. Does it once in awhile seem like it wants to catch and start but no more than that? I am venturing a guess that you may have a bad camshaft position sensor or crankshaft. They can go out and still allow spark to the plugs but because they are delivering the wrong position of the shaft the timing is off.