You don't have 10 titles listed as "Available" based on the post you made. Almost all show a wait of some sort, or are not yet available. You have not given them anything to send you that is "Available" now. Their email to you makes perfect sense. You need to add more, a LOT more, to your queue and your shipping will be consistent assuming you have titles "Available" in the queue. I have three out at a time and something always ships immediately once a return is made. Surely there are more than 11 titles of games/movies you'd like to get at some point, so add them and get something shipped.
Ok. I will look some more. I was going to use Blockbuster for xbox games so that's why I don't have many in there. I thought since Halo Reach is fairly old, that at least I would get that.