It sucks and is inconvenient but it happens all the time. I worked for a company that sold a LOT of items through Amazon. The items were expensive and there was always some fraud. Amazon had their own fraud detection software that would flag orders based on various criteria for manual review. Legitimate customers called, live chatted, and emailed all the time trying to figure out what was going on after talking with Amazon customer service.
A lot of times the agent you speak with really has no clue why you were flagged. It could be because of a different address being used or even past issues with a similar mailing address (customers claiming items are not being received). The best thing to do is wait it out then reorder with home delivery and plan to be home when the items are delivered. I know you are frustrated because you really wanted your order, but imagine how you would feel if Amazon was less diligent and someone was able to use your information to receive a fraudulent order.