Cellphone and customer service

I bought a cellphone for the retail store wishing 3 months the phone started acting up the screen became blank I could not use then phone. I returned the phone at the store and they told me that they won’t refund me instead they will take the phone to the repair okay the phone came back from repairs. In no time again the phone started acting up again I returned the phone it was then booked for repairs again. I am currently not able to use the phone again when I got to the store they said they can only book if for repair and I am the one breaking the phone. My understanding it this phone had a factory issue and foschini is buying time so that the phone can run out or warranty and am stuck with a debt of something I cannot use. I’ve tried reaching out to them on their social media pages but they are not responding. What is it that am doing to make the phone screen dead since am the one breaking the phone. It is very disgusting cause their sale representative just don’t care and they even tell me that it’s my own issue foschini has nothing to do with this but am expected to pay the account each and every month with no fail paying for an item I was never happy with