For battery not to discharge after 50% do this: 1. Discharge your phone completely. If it turns off at 50% then let it. 2. Once your phone is dead, charge it to 100% without turning on the phone. 3. Once fully charged, turn on the phone and use it normally. See if the phone still turns off at 50% battery. If no then let it discharge completely and repeat the above steps. This is called battery calibration. This happens with iPhones as well because I have used one for 3 years. Better to get your battery replaced after 2 years of usage.
My suggestion switch to iPhone. Samsung never cared earlier and will not care now. Cheers Also fyi android update will never be given as your model got 2 major updates since its launch.
