Have any parents experienced a fine/penalty from their childs school for taking a family holiday in term time?

my sister is due to go away in 2 weeks for a holiday of a lifetime!! the holiday forms were sent into school,the eldest child (in secondary school) has had her request "unauthorised". i understand fines,and even a custodial sentence can be actioned against you for this. has anybody out there experienced this? if so what happened and can you offer any advice please? both my nieces have excellent attendance.records,do well within school and have never posed any problems within school. any advice appreciated.