VAT-mod for European companies

[J-A-J-O]

Hello, i've installed this mod on my zencart 1.3.8a store, but i do not want one thing: customers must write their vat numer in following way:

"Contry Code" + "VAT Number"

-exapmle

VAT = PL1234567890

I want to leave just "VAT Number", without the contry code

-example

VAT = 1234567890

I will not get orders from others contries, only from mine, so "Contry Code" for me is useless.

Does somebody know how to do it? Witch files i must modify? I tried to do it for my own, but my php knowledge isn't great.