5 weeks old phone and been 3 weeks with Mr price

I purchased 2 Hisense E7 Pro mobile delivers from Mr price mobile on 29 November 2019, literally 5 weeks ago. Upon purchasing the devices both were gifts. In which I issued the first gift to my mom a week later after purchasing, we set it up on Sunday December 8th we set it all up for her and on Sunday evening she charged the phone and went to bed. The next morning she turned the phone off to remove her Sim card to transfer contacts and the phone would not turn back on. She tried charging it again no indication that it's charging, tried a different charger and that too didn't work. We don't stay in the same area and I work full time. I managed to get the phone from her on the Wednesday and since I bought one for my son tried putting the battery into his phone and it worked I then tried his battery and it didn't work in hers. I managed to get to the store on Friday 13TH DECEMBER 2019 and was advised that the phone needs to go for repairs this is a brand new phone which was less than 2 weeks old and used for literally 1 day it is now 3 weeks later and we are yet to receive the phone. Mr price mobile has not been helpful and we are just told to wait. I would like the manufacturer assistance with this as