Cover not covered

<p>My wife bought an iPhone a while back and was encouraged to purchase a "Life Time Warranty" screen cover at an iStore. The store assistant encouraged her to buy this, more expensive one, as one could have it replaced free of charge if it were to ever crack.</p> <p>Unfortunately it cracked, and when she returned with the original invoice and package to ask for it to be replaced the iStore assistant simply said that they don't cover it anymore. Neither of us expected this from Apple? </p> <p> </p>