Apple poorly manufactured/designed their iPhone 6 Pluses, allowing a problem to start occurring as the phones aged.
This was known as a "touch IC" issue, which causes a flickering grey bar to appear at the top of the screen, and for touches to the screen to be unresponsive. This is an intermittent problem, but once a phone has it, it becomes extremely frustrating to use, and borders on uselessness.
For many months, Apple denied the problem and refused to even offer fixes to it. If the phone was out of warranty, you were told "tough luck" and told to buy a new phone. If the phone was in warranty, they would swap it out for a refurbished model -- which is usually a disaster, because refurbished cell phones tend to be full of problems.
After 4 class action lawsuits (still pending), Apple compromised and finally acknowledged the problem in November, 2016: https://www.apple.com/support/iphone6plus-multitouch/
However, Apple will not acknowledge this was due to bad design. Instead, they blame it on the phone being "frequently dropped", which is BS.
They charge $149 for repairs to fix this out of warranty. However, in some cases they cannot repair it, and they again stick you with the dreaded refurbished phone.
Total joke.
This should be a FREE repair, but Apple is greedy and arrogant, and refuses to do this.
My girlfriend's phone has fallen victim to this, and I'm bringing it in today. We basically have no choice.