Axiom

I have buy (2000 Dirhams) samsung galaxy S4 (GT-I9500) mobile phone on 20th September 2013 from Du Dubai, within one month the device not hearing voice when I receive call, I Went axiom Service Centre in abudhabi They Told Me Software problem And They upgraded, after 2 month the device get again problem automatically shutdown and restarts, Then Again I went Service Center that technician open and check the battery and the battery was becomes very thick, how this samsung product battery with in 4 month's using become thick? And technician told me keep one day, then I kept one day next day I received, now from yesterday not charging battery properly, it's took 8 to 9 hours for full charging, what I will do this device?

I buy Nokia N95 8gb mobile in 2008 (**** Dhs) still I am not get any problem no battery change nothing, and I buy apple I phone 4 in November 2011 (**** Dhs) still not get any problems how this samsung product like this happens? Please advice I contact with whom, I am not interested with this device give me the new device still this is in under warranty.