Thank you for your advice. With respect to rerouting, before I left MAD for FRA they did inform me that AC877 from FRA to YYZ be delayed about one hour, but since I had ample buffer time in YYZ (almost 4 hours) I just continued with my original itinerary, and it was not until I arrived on FRA that the delay had grown to a few hours and then became many hours, at which point there was no rerouting option available from FRA.

[Edit] PS It is actually not the EU Commission who handles these claims, they refer to the local aviation authority, in this case the German Civil Aviation Authority (Luftfahrt-Bundesamt), since the incident took place in Frankfurt.