I'd agree with wowzz. Since every booking web site or agent asks for your email address and mobile/cell number - then they can inform you. As I say, I have checked the web site of a carrier the day before and the schedule had NOT been altered.
This is the way that companies do business these days. Check your paperwork and do all that you can to chase them - but they can still fail you. We have had a long conversation in here last year about the failure of many carriers to use SMS to their advantage.