Can you send it back under warranty, it sounds dreadful?
Have you tried the trick with the fingerprint sensor, of covering it with a piece of sellotape.
But if the screen is unresponsive it ought to be looked at by Fairphone.
Your issues are not what is generally expected, so I wouldn’t lay that as general Fairphone quality, mind you support can be unresponsive and laggy too 
Have you tested the modules etc. by dialling *#*#66#*#*
Service tests > Test single > . . .