Not able to place order online

I'm having the same issue. I'm the primary account holder and I'm trying to purchase a phone and got the same message about billing address...unable to complete purchase…..call support. I've tried two different bank accounts, contacted customer service, and even went in to my local store. Support just keeps doing the same steps I'm doing online and getting the same error so they say there's nothing they can do. The store employee can't physically swipe my card in the store unless I'm buying one of the phones they have in stock there but the one I want isn't available at the store. I'm at a complete loss after trying to buy this phone for 3 days now. It seems like the error is on the backend of their checkout process if other people are having this same issue.