i've just got my timetable through for next year and the guy who does it has only put me down to do 80% of my hours.

i'm well tempted to keep schtum and see if i can get away with it. If i tell them it's likely that they'll take the hours off a part-timer who could well do with them, plus i just wanna get paid more for less work.

What would happen if this got found out? Could i plead ignorance, or do you reckon they'd fire me / take back 20% of my wages.