Bad service and ******ion.

I purchased Apple iPhone 6s on the 29th September 2018 at John Craig Carlton Center. The phone was in a Revive box, by then I gave it a benefit of the doubt because I had a lot of respect for John Craig. Three months down the line (late December) the phone raised as thick as a Nokia 3310 and I went back to the store and the phone was exchanged with no hustle. The very same issue happened on the 30 April and I rushed to the store again. Instead they wanted to downgrade me to iPhone 6 with 32gb, I then told them that I need the very same Rose Gold 6s with 64gb and now they want me to pay them R700 because they are no longer getting phones from Revive but from Apple directly. What I don’t understand is the consumer act that they are following. This is total ******ion and pure cheating because this is manufactures fault not my fault. From the 30th April till date I still don’t have a phone yet I’m expected to pay additional R700. I need justice to be done. It is not fair for me to pay this R700. They cannot tell me that the phone was on special and special has ended hence what they need to do is exchange the phone for free. I am very disappointed in John Craig and the service rendered.