Lost item in an uber. Struggling to get the bag back.

Booked an Uber on Sunday afternoon for my sister. the driver's name Thulani Gave, registration number HY12MHGP, Volkswagen Polo, number ***. My sister forgot her bag in the car, he was contacted via Uber connection and he agreed to arrange for the bag to be brought the next, but that didn't materialize. Uber was contacted via email, and they confirmed with the driver that he had the bag and that the bag with be made available in 48 hours as the drivers are very busy. We are prepared to meet the driver somewhere and get the bag but now there is no communication at all.