GJC Help - postcodes

[walter sobchak]

Afternoon, had my site running a couple of years now and just ran into this problem with postcodes.
A customer put his postcode in wrong and managed to get himself free shipping, not great.
Is there anyway to configure GJC so there's always a default charge in my categories? I've just been testing and putting a single letter in the box generates the right charge, 2 and 3 charge nothing, then anything over 4 letters does charge. Any amount of numbers do not charge, even added with letters if it starts with a number.
Many thanks for any help

[GJC Web Design]

As this is 3rd party you won't get any help on here..

please contact me thru the website with all your details

John