ITS A FREE DIY FIX. It is not your screen or the iPhone 6 plus.
THE DIGITIZER CABLE AND RECIEVER IS EXTREMELY EXTREMELY SENSITIVE TO DUST, GUARANTEED TO CAUSE THESE SYMPTOMS. If your phone is otherwise okay, check and clean the contact clips. Very little room to mess up, be cautious.
My phone was erratic for the longest time. I blamed my cracked screen until yesterday. I put a replacement on, didnt do a thing for this ghost touch/ unresponsive/ works fine/ frozen issue.
All signs told me a parasitic load was interfering. YES IT IS. But it is NOT A HARDWARE ISSUE.
CHECK your ribbon connector reciever ports. ONE SINGLE dust particle interfered with the capacitance on mine.
MINE HAD A TINY TINY SPEC OF DUST WITHIN THE CABLE RECIEVER SIDE. The size was about as big as one of the contacts in a cable, hard to see! I used a razor blade to get it out as it was the only thing thin enough to fit.
WARNING: USE A NON CONDUCTIVE PLASTIC BLADE. AND DO NOT MESS UP THE CONTACTS. My iphone 6plus works like new again!