Cell C repairs

I have sent in two iPhone XS reason was for over heating, I had a struggle with cell c when trying to book in these devices in, one of the devices wasn't picking up on the system as an IPhone XS but as a iPhone 7 which was my previous phone I then assisted cell c with the IMEI number which I thought was really unprofessional, I then had the repair department calling me to pay R48 000 to replace the device yet one of the devices are still under warranty, I then request cell c to send back my devices and I had received them both in a terrible condition shattered screen protectors chipped device and one not coming on at all, I requested cell c to book in the phone that was switching on again as it wasn't the reason for which it went in, I have now being told to pay R18 000 for a replacement which I find terrible as this was something that happened at cell c repairs my phone was working and wasn't the reason for going to cell c repair, I have spoken to the lady who claims she is the manager Dimakatso who wasn't helping at all and said I should pay cell c and she won't replace my device, this is really disappointing and I do not appreciate the service received by cell c. I want my device which isn't working at all to be replaced with no excuses