Help!! If formulas for calculating commission payments

I need to work out formulas for commission payments on a spreadsheet i have set up for the following;

Quarterly Target £225,000
Budget Target £300,000

Quarterly on target Variable Pay £5,500

Paid Monthly upto 100%
If within quarter exceed target the commission for the amount over target will get paid an automatic accelerator of x1.5 and
If within quater exceed the budget target the commission for the amount over the budget gets paid an automatic accelerator of x2

I need to work out the correct formula for the

1) monthly variable pay so that the employee only gets paid upto 100% within the quarter
2)quarterly variable pay if over target or over budget

I really need help as i have to have this done today. We will also use this to send to employees so they can calculate on how much sales they bring in how much commission they will be paid.

Thanks