Terrible Service want our money back!!

Hi, my name is Bathabile daughter of Mavis Serasengwe (***) here to lay a complaint on PEP CELL in Eloff Street. My mother purchased a phone a month ago and since then it has been problems, since the purchase of the phone the phone does not want to log in or access any of the services like google play, emails, play store. She took the phone back 2 weeks ago when they advised that it needs to go for repairs, while the phone is gone for repairs I had to give her my phone cause no phone was given to her in the meanwhile, a week ago she was called and advised that the phone was done with repairs and she can collect after a few days with the phone and us trying again to access the services the phone still gave the same issues, yesterday again she went to take it back and with them failing again to help with the issue they took it again for repairs WHY??? We cannot accept the same phone to be given to her again! We want a FULL REFUND for the purchase of the phone so what we can purchase a phone with another service provider, the service has been terrible from day 1 and my mom cannot work cause she has no phone and due to her not being able to access her emails her catering company is at a stand still. We need an urgent response as to when she can go back to collect her refund, most details I am unable to provide you with due to the phone back and receipt being taken by them.