Software upgrading problem

I have an iPhone 6 plus that is freezing frequently, it is such a frustration, each time new software is available the phone forces me to upgrade, if I do not upgrade the software my applications performance keeps lagging and in time completely stops working, even my App store wont work, and after upgrading my iOS the problems just keep getting worse, my applications are freezing more frequently and the phone is so slow. This is unacceptable as we as iPhone users pay a huge amount of money for a quality phone, I will rather use an Android phone from now on as the software does not force you to upgrade the phone. An Android phone will work 100% correct if a software upgrade is never done. I would like to know what Apple tends to do about this issue as I believe that a product that cost so much would rather work on their performance and not their casing. It is such a shame as the iPhone is an exceptional phone but such a small thing turns into a massive problem.