Driver stole my phone

about a month and a half ago I was stranded at a garage and asked one of the ladies there to order a bolt for me from highveld centurion to randburg. upon arrival at home i told the driver i would go and get the money from my house. my husband further went on to explain to the driver that the money in question would only be available in about an hour, the driver made a big fuss which is understandable and so we offered for him to hold our phone and we would call him to come and pick up his money to which he agreed. and now it's been a month and a half and the same driver still will not return the phone at this point if i do not get the phone back within 24 hours i am now obliged to open a case of theft. the trip occurred on the 8th of July. and the phone was a Nokia C 20 which had a lot of personal information on it. i personally have used your service for years but this is honestly beyond me to have a driver ***** my phone so bluntly. i am hoping you as a company can assist me in order to avoid me going to the authorities. the REG f the car is LJ15LFGP its a hyundai grand i20.