So Called iPhone touch disease is usually caused by the board being put under stress and causing damage to the touch controller ic/solder joints or pads. This became a issue in the 6+ as the frame was so thin even having in your pocket and bending over could cause this. This trend has continued in the bigger iphones but is particularly popular in the 6+ as it seems to damage a number traces under the touch controller ic.
We can professionally repair these pads and traces if needed and replace the ic to restore touch to your device.
Please see the services or shop for further details.
http://www.bbc.co.uk/news/technology-38026003 This is a report from the bbc covering the extensive problem.