Tmobile just updated my preorder to backorder, this also happened to my iPhone 5s preorder.
Incase this happens go to any store and if you are lucky they'll find a phone and all you have to do is cancel the order through phone or store and get it in the store.
Incase this happens go to any store and if you are lucky they'll find a phone and all you have to do is cancel the order through phone or store and get it in the store.