BB Bold 9700 :: UK Postcode Entry / Phone Not Allowing Numbers To Be Entered

I got my first ever BB yesterday, the Bold 9700, but there's a problem with the address book which is driving me nuts! Despite setting the phone up for all available UK localisation options on the startup wizard I cannot enter the postcodes of my contacts in the address book. The field is labelled "zip/postcode" but will not accept letters, just numbers as would be the case for a zip code. I've tried to override the number lock which is the default for this field, but the phone will not allow it.

I've rechecked the "options" folder and the "advanced options" subfolder, but there is nothing which gives me an option to overcome my problem. For those unfamiliar with UK postcodes, they mostly follow the format AB1 3XY but some have a seven character format AB12 3XY. BB's have been in the UK for ages so surely someone knows how to fix this issue, unless it's specific to my model which I understand hasn't been out that long.