We have a customer who wants to purchase an item from us. She said she set up an account, but when I look at her profile, there is no billing address listed, only a shipping address. She said that she has put in a billing address, but gets an error message saying that the address doesn't exist. She also gets a message saying that we don't ship to that address. We have shipped to other addresses in her state (Florida). How do we remedy this problem. She wants to buy an expensive item and we want to sell it through our website.