Well the bike will have been built by Cannondale then assembled by Evans – literally just a case of put the front wheel on, straighten the bars, make sure everything is tight and the gears and brakes work, tyres inflated etc. 30 minutes work.
So presumably the bike left the workshop in pretty much perfect condition – it’s not uncommon for things to work loose after a little while, that’s why shops offer a free first service.. Sounds a bit shit that the hub fell to pieces that quickly but again, that’s Cannondale. You can’t expect the shop to pick up on a part that functions perfectly to start with then maybe caught on something, took a knock while out riding (or in the car).
I’d accept it as one of those things, get the shop to sort it and carry on with life.
FWIW, when I worked in a shop that sold Cannondales, we usually expected to get them back inside of a month due to them being utter shit. For that reason, I would never even consider buying a Crack’n’fail…