Please get in touch so we can investigate. It is difficult to provide accurate delivery charges for all order combinations for every destination in the world, especially if you are ordering numerous items that are small in size and weight.
This is due to products being held in our system with gross weights (i.e. including the weight of the packaging). Unfortunately it is a system limitation that we have to live with for the foreseeable future. For larger items it is sometimes cheaper to place it all in one box, other times it is cheaper to break it up into a number of smaller boxes.
We also use 8 couriers, so there are a lot of combinations to investigate.
So, please bring your concerns to our attention and we will try to promptly resolve by adding a more specific rate to address your order.