This worked for me after all had failed (user information, billing information, postal code, etc)
believe me i tried them all with no success.
Just call the account helpdesk in the US and ask them to remove your credit card from your account (takes about 5 mins).
When this is done buy points through paypall (paypall can be linked to your credit card = no problem) or another payment method supported in your country.
Whatever you do, do NOT put your credit card information back on your account, this was the blocking issue for me.
Believe me i spent days trying to find out why this was not working, contacted my credit card company, turbine helpdesk everyone but it didnt get resolved.
So i thought ok then i'll just remove my credit card from my account and buy points with "other payment methods" that were supported in my country.
But to my surprise i was just able to buy points again through paypall (that was still linked to my credit card and that wasnt working before either) with no problems.
So this might work for everyone else who have tried everything already.
Hope this helps everyone out there having problems with buying points.