Online istore pre owned poor service

On 10 November 2023 I purchased a device IPhone 11 Pro R11.999 at iStore pre owned online, it was delivered. On the same day after openning the box I saw the device and realise that it is not what I wanted basically I wanted IPhone 11 ProMax.Within 7 days I logged a call return call via email and I explained to them the error and informed them that I want to get iPhone 11 pro max even if I need to top up. I received an email that was sent by Ayanda Zulu stating that courier has been arranged with Skynet to collect the device on the 27/11/2023@14h01. I have been waiting since that day they never arrived and no communication has been made. I tried to rich out to them Via phone calls and emails not getting any response instead on calls they are giving me a run around. My reference number is PGL54388 and the case number is ***8. Can I please be assisted to get the device collected so that I can be able to purchase the device I wanted from them.