How to stop app contacts being deleted

No more than two months ago I updated to iOS 9.0.2. I have an Iphone 4 and ever since it hasnt been working correctly. It keeps turning on and off, freezing the battery is useless and most frustrating of all Contacts in all my apps keep getting deleted, e.g jellybean, whatts app, facebook, viber and snapchat. When it was just facebook I thought maybe someone had hacked my account, but now that its all my apps I don't think so anymore. It seems like random selection all though some contacts do over lap. I have changed all my passwords and its still happening! Different apps on different days.

Is anyone else having this problem? or does anyone know how to fix it?