Improvement suggestion: Country based on user location

Steps to reproduce:

1. A person living in Finland loads the Payson check-out page
2. Payson loads the default option “Private person”
3. The customer naturally fills in his/her email, Finnish social security number, and Finnish zip.
4. Clicks next.
5. Payson throws an error, due to the social security number being “incorrect”, and advices to select other option. “V?nligen kontrollera att ditt personnummer ?r korrekt och skrivet p? formatet ??MMDD-XXXX. Om du handlar som f?retag eller inte ?r folkbokf?rd i Sverige s? v?ljer du det i boxen ovan.”

Suggestion on how to improve the solution:
A) A better error message – current message actually does not give clear directions to the user
B) Validate syntax of social security number directly when user enters it (it should be possible to tell the difference between Swedish and Finnish soc.number with regexp) – this would give the user quicker feedback that something is wrong.
C) Preferred: Use geolocation to select correct type of customer – If user is located in Finland – set “Other option” as default.
D) If “Other option” is selected, use geolocation to set country.