MTN Nokia 3.1 bought at Foschini

I bought an MTN Nokia 3.1 cellphone from Foschini on November 25 th 2018. The phone worked for 13 days then it stopped charging. I took it back to Foschini and they booked it for repairs. I had to wait for 2 months full to get my phone back in February 8th 2019. The phone worked for 11 days then gave me the same problem again, it was booked in for repairs again on the 20th February 2019 and was promised by Foschini that if the phone gives me the same problem again, I will either get a new device or a refund. I then got a call yesterday (19 March 2019) that my phone is ready for collection. I then went in today(20 March 2019) to collect but the device was still not working although they said that they had replaced the inside of the phone so the phone was as good as new but it did not even leave the store. I spoke to Foschini and MTN and said there’s nothing that they can do because the phone was repaired by Nokia, so they had to book it in again for repairs. I don’t know what to do anymore I have tried everything. Please help because now I bought a phone 4 months ago but I don’t have it. I have only used the phone for 14 days plus another 11 days, so that is a total of 25 days for a phone that I bought almost 120 days ago.