I have a iPhone 5C and for not so long ago we repaired the screen for the 3rd time after my sister threw it on the floor. And after we repaired it at a place nearby it sometimes don't respond to touch and do stuff on it's own. We wen't back to the place where we repaired it (who is not using apple's own screens) and they thougt it was because of fat on the screen. I googled the problem and one site said the problem could appear if you had a fake screen (not apple). What is the problem and how do I fix it? If it is fat could a glass/plastic screen protector work to keep the fat away from the screen?