[Paul]

Update: After communication with the Austrian Airlines customer centre, the airlines credited my credit card by all the airport taxes paid - I did not have to fill any form and they did not charge any fees for that. Definitely a positive point after the troubles.
Of course, it does not change the fact that, if the airlines already "must" have this flight cancellation rule, they should at least notify the customer that they are going to cancel his flight and it also would be nice if they mentioned this rule specifically eg in the confirmation email (I have recently ordered a flight at Swiss airlines and they manage to mention that, thus certainly Austrian could do it too) - at the moment it is only mentioned once, buried in the middle of tens of pages of the general rules... and clearly, majority of people is not aware of it at all. I will continue suggesting these changes at the customer centre - who knows, there is always a chance it could help.