iPhone 6: Unresponsive Display

Hey there,

I've got a refurbished iPhone one month ago after having trouble with the camera.

Everything was fine until three days ago, when suddenly my iPhone started to not respond to my touch gestures. Since then it happens multiple times while using and lasts at least 10 seconds. Sometimes minutes.

My home button works fine, even when the screen seems to be frozen.

I tried to reinstall iOS and set up as a new iPhone without any progress, so I went back to my backup.

Does anyone knows what to do? I just made an appointment at an Apple Store nearby..

This would be the fourth appointment since I got my iPhone 6 in Nov'14...

Do you have any good advice? I don't want another screen replacement on my new iPhone, because my last iPhone had 2 screen replacements and every time, the same errors came back...