Ever since iOS upgrade on iPhone 5 and iPad mini it will not stay connected to wifi

Ever since upgrading to iOS 6.0.2 on iPhone 5 and iPad mini neither will stay connected to wifi. You constantly have to go into setting and reconnect to the wifi network. This is a HUGE problem on the iPhone 5 because it does not stop working and you end up going over on data!!!! Fix this soon Apple. This is the worst iOS upgrade ever it was supposed to fix problems with wi-if but it creates problems that are even worse!!!!!!