Lost iPhone during repairs

I took my iPhone 6s for repairs on the 25th of July 2018 at the Wefix mall of Africa. When I went to collect my phone on the 27 September 2018 and I was told to come back the next day because their technician had locked my iPhone in his locker and they couldn't get hold of him. Now we were told that the phone is lost and they are doing investigations. Its been 14 days and no one has got back to us or even told us their findings on the investigations. I've spoken to 2 assistant managers and a regional manager but they all tell me the same " we still running our investigations on our side" story.