Disgusting service

I sent my cell phone into Samsung on the 27 October 2017 for a cracked screen. It was told to me that the repairs will take 5 working days. It was then sent to Utronics (Samsung repairs at Century City) I sent the POP. I never got a response after 2 week which I then followed up, no responce. I then emailed again to follow up and only got a response a week after that to say my POP wasn't receieved. ( a month delay) I then sent through the POP again and still nothing. I emailed on a daily basis to find out how long the phone would take as this is our CEOs phone! I eventually got a call to say I could collect the phone from Samsung in waterfront where I had originally dropped it off. This was on the 20 December 2017. When I collected my phone the sim tray was missing which I know for a fact I gave the phone in as a solid unit. Nothing was given back to me to keep while the phone was getting repaired. I contacted Samsung repairs to find out where the SIM tray was and it was then mentioned that the SIM tray didn't come with the phone. How do I argue this point??? I then asked to purchase ANOTHER SIM tray and was once again said that it will take 5 working days. I'm STILL waiting for my sim tray two weeks later! Once again no response to ANY emails. Samsung head office, Century City is disgusting with their service and I'll never purchase a Samsung again.