That did it. Thanks....
Now checking different shipping scenarios and I'm not sure the fuel surcharge is working correctly. We're after:
Fuel surcharge = 13% of the parcel value added on at the end.
In the calculation we have:
($_SESSION['ShipZoneFuel'] * ([Price] * [Quantity])
should that be of the [Subtotal] rather than each [Price] * [Quantity] and if so is the subtotal written correctly?