Payroll sheet with Canada Pension Plan calculation that needs fine tuning

I have set up my payroll spreadsheet so that all I have to do is enter hours worked and it will calculate the taxes, cpp , ei etc. I have the tax brackets working ok, my problem is the formulas for Canada Pension and Employment Insurance.

CPP is calculated on earnings over $3,500 and stops calculating at a maximum of $46,300. I don't know how to start the calculation on a running total at $3,500 exactly - I can only get it to start in the cell that is greater than 3500 - ditto with ending at 46,300.

The total maximum deduction for CPP in the year is 2118.60, so I entered a second column to do a final check and balance the amounts. I have attached a spreadhseet with the VERY ugly CPP and EI calculation, that I am hoping someone will be able to refine.

The employment insurance column has the same problem, but I can fix that myself if someone can teach me the fix for the cpp (I'm like a very bright trained monkey!).