Apple India — iphone 6 a disappointment

My iphone 6 is of no use now. I never knew iphone would have been such a disappointment. My phone hangs continuously. Every app at least needs 30-5 seconds to open. You can open certain apps. While you are working on some apps it crashes suddenly. The battery gets hot. It's not getting charged properly. It is terrible. What about apple being a long term use product. This is such a disappointment. What solution do you give me for this?