I am facing a similar situation, my flight from XRY to MAD was cancelled due to the aircraft going tech, and IB claims extraordinary circumstances.
Go early JAN and my BA flight from XRY-JNB was cancelled by BA, the email I recieved as I write States bad weather, my arse... My flight was scheduled to leave 1820, there had been fog in the morning, my flight cancellation was the result of knock on scheduling.
There is too much ambiguity in the current EC rules, they need to be revised and tightened up for both carrier and passengers sake. As I have tried until my wits end to explain to the stupid spanish side of IAG."you piss me off any further, you loose business"
In both cases I am reporting the carriers to the regulator as the response is unsatisfactory.