This happened to my Mum many years ago (not getting sacked). She told her Dad she was doing school work with her friend but was on the TV news screaming in the front row of a Beatles concert and her Dad saw it
It seems a harsh sacking - I think a lot of people have chucked a sickie in their life and its a chance you take that when you lie to your boss. I think very few employers would have dismissed for this (especially if they were football fans) but there could be other mitigating circumstances - she could be a serial sickie puller or have been on a final warning.