It is absolutely ridiculous that Fedex does not accept debit cards as a form of online payment. And they don't even clearly communicate this.
You can waste a huge amount of time getting your order together and once you're finally at the end and entering the card information it will reject it upon clicking "ship". Horrible business model.
At least specify this up front so that the customer does not go out and buy the fedex box and deal with collecting address information and spend the time entering everything in before rejecting their debit card. I will not be using fedex ever again