Shipping templates for FBM inventory

Has anyone got a solution to the shipping templates in the UK for large items.

We have a new 2 man courier coming in, and they all have set rates for mainland UK then additional rates for out of area postcodes.

What confuses me is that Amazon bungs together England/Wales and pretty much all of Scotland, all the way up to the highlands till you get offshore separation.

For some of our items we are charged up to around £127 extra by the courier to ship to parts of Inverness, or offshore Paisley postcodes (which amazon bungs together with onshore Paisley postcodes) but Amazon wont let us set a rate for these areas as they say 'There are some regions, for which you have not set same charge.'

I don't understand why Amazon let you separate them out into regions, but then force you to use the same shipping tariff for the different zones??