Hello,
The last sentence was an interrogation, so you can perform some tests in order to check and confirm.
Thus I do think that you might have a similar issue with customers in UK who gave a VAT number.
Because if you do have the same issue ; it's something you should report to the HikaShop team ; I can't provide a fix in HikaMarket.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.