Touch screen unresponsive and glitching.
How much would it cost to repair my IPhone 6 plus if it is unresponsive to touch and presses random buttons on its own? I do not have a warranty or insurance for it.
iPhone 6 Plus, iOS 11.2.5
How much will depend upon what country that you are in, and whether the problem is not just the screen (I assume that you've already tried the 'standard' troubleshooting to see if it fixes it). Here in the UK : iPhone Service Answer Center - Apple Support