Forced to accept factory faulted phone

I bought an iphone 7 plus in telkom. Tygervalley in 17 july and it gave me a problem that i had to take it back the following day and they told me to do sim swap i did that 4 tymes in a period of 2 weeks before the phone literally stopped working on the 28 july i returned the phone and they refused they told me that the phone doesnt have warranty and i must claim from my insurance which i refused and they took ot for fixing and they said it was fine . i took it bck and same day it gave problem and they have been billing me for what i dont have and i refused to pay and they said they are taking me to credit burrow ...and in the process i have been logging calls in their call centre but they all rrfused to help me and i just dont know what to do and i still dont have a phone and im still recieving threatning sms and calls ....and when i went to the store the manager refused to help me and told me go he will make a follow up even today nothing has been done and telkom Tygervalley their service is poor and they have race issues....matter has not been escalated for almost 3 months now when ever i call they just keep on updating the case and it has not been resolved even now no communication