Call apple care, explain your situation. If they do not offer an exchange then ask to talk to their manager, if he/she do not offer an exchange then ask to speak to customer relations, explain to that person what you have gone through and ask to have it exchanged.
People gets parts of their laptop exchanged when cracks developed too, so therefore its not unlikely that a crack develops in this type of material.
If they still do not offer an exchange, your options would be:
a) return the product by paying the restocking fee, then may or may not go and buy a new one.
b) make a big news out of it, sending photos and stories of your horrible experience with the newly opened apple store to online tech blogs and local news papers, and apple will offer you a new iphone before you know it.