Xperia Z2 :: Can't Make Calls / Dial Button Does Nothing - Two Phone Apps In App List

I was still on kitkat on my xperia z2. One day, when trying to make a call, I just couln't anymore. Basically, I can bring up my contact list, recent calls etc. But when I go to press a contact, which would usually start ringing them, it does nothing. If I manually enter a number with the keypad and press the dial button - the keypad disappears and it isn't dialing.
 
I tried restarting my phone, which will then allow me to make calls as usual, but as soon as I close the "phone" app and open it back up again, same problem - pressing contacts/ dial buttons etc will just do nothing. Every time I restart my phone I can pretty much call someone once and that's it.
 
I went in to my apps list and founf something very strange - two standard "Phone" apps. Why there are two now, they are also different sizes (one is 1.11mb and the other is 2.0mb). I obviously cannot disable or uninstall either of them. I don't know if this is the problem.
 
I have updated to lollipop, thinking maybe that may work, but everything's exactly the same.