Fiona J - I agree that one product in a blister pack should command one prescription charge and not two. Other products - like menthol and eucalyptus for colds, or glucosamine and chondroitin for arthritis, don't command two prescription charges. If two or more products work together to create a remedy then it is still one remedy - and therefore one prescription charge. There is a real point of principle here.
Don't pay it. I have had the same thing but I think it is only certain chemists that are trying it on. Boots the Chemist does it and I have just refused to pay it. We do not pay per chemical - we pay per prescription in this country, and we really need to hold on to that by refusing this "con". We can shame Boots the chemist if enough of us refuse and make a fuss about it.