We use a courier that charges two different rates depending on the area of delivery. They have a list of Major Centres (12 large cities) in our country and the other areas are Regional Centres.

They have a rate based on weight if delivered to Major Centres, lets say for every 1lbs it costs $3. Now if you require a delivery to other regional areas, they charge the normal $3 per 1lbs + an additional surcharge of $2 per 1lbs.

I have my two zones setup already, but cannot seem to find a shipping module that would do what I want to do. Would I have to custom make this? or can someone shove me in the right direction to get this working.