in iphone x network issue outgoing issue if apple support didnt resolve the issue why they said this is apple

Dear sir ,

i am apple user since i used first mobile phone ,i sed iphne 4,4s 6 6s now i am using iphne x ,when i purchase after 2 months i getting issues screen issue after that i give my mobile phone in hyderabad aptronix they will fix ,but after fixing mobile phone is getting heat ,now i am facing network issue & outgoing issue ,2 days ago i contact with apple support they called me but after 1 hour call no solution apple support team said me reset mobile phone again i am facing same problem ,kindly need u r assistance pls thanks