pep cell

i bought a phone in december and last week, it just went off. i took it back to pep home mall of africa and they said it will take two weeks for repair. today i get an email saying its out of warranty its not even 5months of me owning the phone. i asked the repair company and they say its water damage. i emailed back stating i never dropped it water or it has not been in contact with water and they rep**** saying maybe its "mist". i just feel im being reaped off and they trying to make money out of this repairs. i have owned samsung mobiles and this is the first time i had a issue with a phone within four months and now im expected to pay.