Blurry IPhone 6 Plus Camera

This is so aggravating! I've had this phone for 4 months and I'm so aggravated with it! I had to swapnit 2 days after getting it .. I had problems with the battery so I returned it 2 days later and got another one, well now, the back camera will not focus and I searched online and a lot of people have this problem. Are they going to charge me to swap? I have insurance & apple care but I refuse to pay for something that is not my fault. I have never dropped it or anything. The only problem is that the Apple has scratches on. Will they still take it back ?because the battery died so fast.