Shocked with Apple Brand and bad service

Did an upgrade and got 2 new Apple Iphone XR's in November 2019. Since then the WIFI button has been disabled and grey'd out 4 times, and have had no connectivity to WIFI or Hot Spots whatsoever! Took the phone's in to Vodacom who said it seems to be a software issue / glitch and wiped both phones, did restore etc. WIFI then works for a period of a week or so and then the same issue happens, WIFI button not working and grey'd out. I have been to the Apple Store in Gateway to discuss this ongoing issue with the Technical Team who just say "they don't know what the problem is" and I must book the phones in to be assessed at a cost of R450 per phone! I am disgusted that everything requires a cost, even though it is is an Apple issue and NOT a user issue, the attitude is "please pay and we will look at it". I have tried to reach out to Apple USA, but it seems you can't reach them from SA, very hard to find any contact details for their HQ.