This sounds simple but I have been pulling my hair out trying to figure out a solution. Any help before I go bald would be great.

I need a formula which is able to calculate the duration in (days, hrs, mins) between two date\time values (eg 05/12/2012 5:30 PM and say 07/12/2012 5:45 PM); excluding weekends and holidays. I would like the result of the formula to read as follows "e.g 2 Days 0 Hrs and 15 Mins".

Bit of context. Trainers delivery courses and mark the courses as ‘Completed’ in an electronic diary system. The diary records a date & time stamp of when the course was marked delivered. A penalty is payable if a trainer does not mark a course as ‘Completed’ within 24hrs of the end time of the course. This 24hr window excludes weekends and holidays (i.e if the course ends on a Friday at 5:00pm they have until Monday 4:59 pm to mark as delivered). Technically a trainer can mark a course delivered up to 2 hours prior to the end time of the course, so this would result in a negative figure if you did a simple ‘End Time’ minus Completed Time’

Elapsed_Completion_Time.xlsx