1) go to settings

2) on the search bar add: apps

3) Select option: apps

4) Select: "more" option. The  3 dots at the bottom of the screen

5) select: show system processes

6) select: dialer

7) select: Storage

8) select: clear data

This should resolve the issue. 

Hi Deon. Check your contacts, make sure it is showing the correct list. Also, go to Settings > Apps > look for the Phone app > Clear data. If problem persist, please directly contact your carrier, the problem is probably on their end.