Was sold a broken phone from EXACT

I bought a Sony Experia l1 at EXACT in lusikisiki On the the 4th of February 2018 I charged it for the required time as soon as switched it and started downloading Apps the battery became in just one hour. I took it back to EXACT on the 6th because it was apprent that i was sold a broken phone they took the phone saying that they taking it back for repairs . I got it back on the 9th of March 2018 but its still doing the same thing the battery is still malfunctioning and it over heats . What do i do ? Is it fair for me to purchase a dead phone from EXACT , I need a phone that works ASAP . Very dissapointed EXACT sells broken products.