Can anyone help please?

I am trying to prepare a report for payment calculation for short term
continuous work. We are using 3 different shifts, First shift 06:00 - 14:00,
Second Shift 14:00 - 22:00 and night shift 22:00 - 06:00. The rate for first
& second shifts (day shifts) is same but night shift is double to day shift.
For holiday night shift rate is using. There is no specific time for start
and end the work. E.g. 07/11/07 09:36 - 10/11/2007 16:00. Please help me to
make a suitable formula for fined out the total amount to be paid for work.