Percentage Calculations Based On Times

i've been viewing different formuals, and have to admit there is alot more to excel than I originally thought, and totally stumped as to what and how to go about my problem.

I have a problem, and it mainly stems from my employer not paying me correctly (and pretty much the other 1600 odd employees encounter the same issue too on a semi-regular basis).

To give you a run down, this is our complexed pay system

Mon-Fri, if you work up to 7h36m you get 100%, then 150% until 10h36 and then 200% after 10h36m working time
Sat, if you work, its 150% upto 7h36m and then 200% there after
Sun, double time all shift
But to throw in some complicated things, here are some more items that need to be considered.
If you work from one day into the next (say fri into sat, and sat into sun and sun into mon, then after midnight, it then goes to that days rates)
If you work your day off, say a weekday, your then paid the eqivelant of saturdays rates unless you were called in straight away which then is sundays rates
If you work your day off, say its a saturday or sunday, then its 200% for the whole shift.
And then public holidays, its 250% upto 7h36 and 300% thereafter

So as you can see, its pretty complicated, and my employer (a government employer) can't seem to get the right software to pay us correctly, nor can the poor employee sometimes work out if they've been paid correctly or not.

So, this is what I have so far:
columns: Day, Type (normal day or work day off or work day off immediate), On1, Sign Off1, Sign On2, Sign Off2, Sign On3, Sign Off3, Working Time, Paid hours
(for instance its my normal rostered monday, I start at 12pm, lunch at 5, return at 545 then finish at 915pm, which equates to 8h30m working time and 8h57m paid time) - the 3rd sign on and sign off is if we do extra work beyond our shift.

There are other things aswell like allowances, but thats for another day, and not as urgent as what i'm really looking for.

Now if anyone can understand what i've just written above, your doing pretty good (even some of the most experience employees still don't understan our pay system), and anyone able to produce a formula for what i'm looking for, i'd be exceptionally grateful, and probably the 1600 odd other employees too who seem to get shafted occassionally.