No warranty replacement phone after 7 months

In August 2017 my IPhone went on the blink. It was sent via the local MTN store to MTN for a warranty replacement and two weeks later I received a long coed which was said to be the warranty replacement approval code. Eventually I got out of MTN the fact that CCI south afriva were the selling aganet ant they would handle the replacement. Thats where the fun started. Numerous calls to CCI from December to taday - asking what is happening to my phone. Now their story is that they do not have stocks of that phi=one (IPhone 5S) and would contact me when they got stocks. This has been going on for 3 months now - each time the same story - no stocks. I asked that they investigate providing an IPhone of equivalent cost and function (eg the iPhone SE). Again there was no action on this request. Today (23rd April 2019) I again requested a replacement equivalent - to be told they are "awaiting a response from the courier) However - they say when you phone them that they represent MTN - ha ha ha - said they must then contact MTN for the replacement as I am still paying MTN each month for a phone I dont have. In effect they have stole my phone as I sent it to them and they have not given me the warranty replacement as per the contract. So afer 7 month NOTHING from CCI