We are trying to set-up a sale on products that are priced by attributes. The sale is as follows:
Products priced between £8.00-£10.00, £1 off
Products priced between £10.01-£13.00, £2 off
Products priced over £13.01, £3 off

The products all come in different size bottles (7ml, 15ml, 32ml)We wanted to show the actual price for each in a drop down menu, so set the base price to 0 and then the actual price is associated with each size (Include in Base Price When Priced by Attributes YES and Apply Discounts Used by Product Special/Sale: YES). However currently the last discount is applied to all products regardless of price, e.g. have £3 taken off when a sale is applied.

Our sale options have 'Apply Sales deduction to Specials Price - Otherwise Apply to Price' Set.

Our test bed is local using v1.3.8a and our question is, does anyone know how we can get this to work in the manner we require?