Unable to buy ZP

For last 3 weeks I'm trying to buy ZP, but with every credit card method [ Paypal, Buddie shops...] I get error "This transaction has been denied.
Reason:Failed to pass security validations.".

There is nothing wrong with my credit card, and I sent 2 support tickets on which I got same reply " Please contact BuddieShops Support at support@buddieshops.com", which is funny because I can't buy with Paypal or every other method, not just with Buddie shops.

So, does anyone know what is going on?

I know it isn't just me because my friend can't buy either.