Getting shipping to order large letter OR package, not both?

Hello all,

This may seem quite trivial but I'm using the Royal Mail mod and I sell small and large items. If I have both the large letter and package options on it offers both to my customers and obviously they will pick the large letter option as it is cheaper but some items are to wide to fit as large letter. If I use just the package option it charges stupid amounts for my small items.
Is there a way to set zencart to differentiate between what an item should be sent as by a width option or something?

Please help :(

Thanks
Kerry

The easiest solution would be to use the Advanced Shipper module from Ceon which allows you to restrict certain products/categories to certain delivery methods. However, as it is a commercial module (though not expensive), forum rules prevent me from giving you a direct link or going into more detail.

Or you re-code the Royal Mail module to understand which products fit into large letter/ package options, but as a non-programmer, I couldn't give you any further advice on that approach, other than to say it's not a quick fix.