In reply to nickinscottishmountains: ^^ this. you are almost certainly not going to get a refund, it sounds like the crossmax's just dont fit you, perhaps ask to speak to a different member of staff in the shop?
unfortunately sometimes you just cannot tell in the shop, and even if they feel great something then might arise whilst out running in them. In this instance just chalk it up to experience and try and remember that it gives you something to think about next time you're trying footwear on, and that you are more likely to find something just right for you.