Aristoph,
Since the flight was cancelled due to light load don't you qualify for compensation under the EU rules as well as a full refund?
Also if the ticket was paid by a credit card they may also give yuo some sort of compensation from any free travel insurance that the cardholder may be entitled to. On 6 hours delayed Copenhagen-LHR flight I received ~£80 from my credit card's insurance company for flight delay and luggage delay.