Paypal Guest Account Payment

Hi

We have small site with a paypal checkout option, all has been fine up until last week, where a customer managed to purchase a product in the UK but get the shipping address changed to the Netherlands, According to paypal this is not possible unless they used a "guest" account where they do not hold the customers records.

The customer was able to by-pass shipping fees as the shipping fees are applied to the currency the product was purchased in, (we ship freee to the UK)

Has anyone else experienced this?

Many Thanks