DID you book through a travel agency? Just asking... most airlines only inform the passengers that booked directly through them (1800 number, website, etc). for passengers that are booked through a travel agency they sometimes (to the best of my knowledge) inform the travel agency and the agency then contacts the customer. that's why the agencies get a portion of the price of the ticket and a portion of the responsibility. Not an excuse but just a possible explaination.

and airlines do have schedule changes from every month to every 3 months. sometimes more, sometimes less.