Contact names not showing for the calls and messages
Had the same problem with GF's phone. The problem was caused by an update. There are talks of a possible fix on Vodafone.com.au forum via upgrade but the simplest solution, instead of waiting for fix (which may never come to all carriers), is to do a factory reset.

Make sure to make a backup of your phone before doing it because everything will be gone.
Step-by-step for factory reset is available here.