I will repost my answer for bcarterbiz which might be useful for tabo603:
My assumption is that you're a 'victim' of a poorly operating General Fraud Protection system.
We're currently trying to figure out either the main cause of orders getting canceled or means of preventing this from happening again - our support team is looking into this right now, and we will do our best to tackle this issue.
I can only recommend you this Hot Fix:
You should contact your suppliers privately and ask whether it is possible to make orders just by sending orders in Excel file and pay for them via Paypal. Alternatively, you can try to use VPN or a bunch of different bank cards (which you've tried already but this might be read by others who haven't).
I'm assuming that orders are flagged as fraud, and eventually canceled if the system thinks that someone has a stolen American credit card and places an order to be shipped to their home address (American credit card - delivery to France). But orders shouldn't be blocked if someone is placing an order with their home credit card and ship order to the US (French credit card - delivery to the US)
Although, this is just an assumption and provided information might not cover all of the reasons why this might be happening. I just want to let you know that we will do our best to find a cause of this and then a working solution!