Iphone giving problem and Istore Tygervalley poor service

I have an Apple Iphone 11 and it was taken to the Apple store and the Vodacom store for problems which was established. Please refer to case number ***. I took the Iphone to the Istore within my warranty period and the service was pathetic and the could not find the problem. Then I took it to the Vodacom Repair Centre and they confirmed the problem but this was done after the warranty period and they are now saying they cannot do anything. Both really bad service. Now I am paying for a phone that I am not using. PLEASE CONTACT ME