new phone dead

My brother bought iphone 5 on q contract and before a year passed the phone died . He went to apple store in menlyn mall and somewhere in johannesburg. He was returned to where he bought it. Whats irritate the most us that mtn store also said the is nothing they can do to hlp him until today which is 2yrs later. A new phone died without explanation. Being desparete we took it to a repait store and advised that nothing can be done. Its dead for good. Can iphone explain whats happend pls. Can this be factory fault.we need hlp please this too way too long.