iphone 6 red screen of death

my iphone 6 started showing me some red screen and then doesn't respond. I took it to MTN but was advised to ask Apple about this problem before having to pay for repairs which could be due to the factory fault. after having googled the problem I realized that these is a very common issue. I went to Eastgate to find out more about the matter, and the only thing I was told was to take the phone back to MTN, and I will have to pay for it. my complaint is that why do I have to pay for repairs for an issue that seems to be a common problem with this phone, is it not a factory fault on Apples side. there was not even an explanation of what could be the course except that maybe I dropped the phone so this is a hardware problem, I am disappointed that Apple could be selling us defect goods and we have to pay for repairs for problems we don't have explanations of.