this is odd, I have just had a look at flights at that time and they are still selling flights for the preceding and following Saturdays.
Are you sure that it's a cancellation and you have not been bumped because it is over subscribed, either way it's a liberty and so are the prices.
Ah well it's the law of supply and demand " we have all the supply and we can demand whatever the f**k we want ".
Time to plough through the terms and conditions and good luck with that.
Chin up fellow traveler.