Hisense warranty fault complaint

I upgraded to hisense h30 lite last year which i got in august. That december my phone screen started to glitch when it gets hot. I factory reset the phone but the problem insisted. After that i started to experience charging issues. The phone cant charge at all. And by april this year the phone showed me a message on the screen saying init all failed:return 3. I contacted mtn and they said i should bring phone in for repairs. When i took it in they told me they are not repairing it the phome fell. After a fight i left the store. Long story short i contacted hisense and they said i should return the phone to the store for free repair. I managed to eventually get the phone booked in at the store on 1 july. The phone was lying at the store for three weeks before it was picked up. I waited for a whole two months for the phone. They called me 1 seltember to pick up the phone. Not saying anything else i checked the phone and it was still not fixed. I contacted the repairs centre and they said that it was rejected due to wrong booking from the store. Eventually tosay i bolked the phone again they said its not warranty its out of warranty. I showed them the emails from hisense. Mtn told me that they should have replaced the phone but they didnt . What do i do now as i know this is only the start...