I have samsung N71AP processor which lags and drains battery . I want an explanation for cheating customers like this

You are not addressing to Apple here. This is user to user forum. You may send your feedback to Apple. They will not respond but at least they will know your opinion. https://www.apple.com/feedback/

Try to follow the instructions on this page in order to maximize your battery life:

http://osxdaily.com/2015/09/21/fix-ios-9-battery-life-problems/

https://www.apple.com/batteries/maximizing-performance/

http://www.idigitaltimes.com/ios-82-battery-life-problems-how-fix-quick-drain-is sues-iphone-ipad-and-ipod-422229

Try to reset your device. This won't delete your data stored on the phone.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

You may also try to reset all settings: go to Settings - General - Reset - Reset All Settings

You may also try to follow these steps:

1. Navigate to settings/general/ battery usage. Check the applications. This will show you which app eats up your battery.

2. Turn off iCloud keychain: Navigate to Settings/ iCloud/Keychain / turn it off.

3. Limit apps activity on the background: Navigate to Settings/ general/ Background App refresh/ turn it off for each application which uses to much power.

4. Disable auto brightness: Navigate to settings/ display and brightness/ auto-brightness. Turn this option off.