I had a similar experience on Facebook marketplace, where the "cousin" did back off because he realised that I was not an easy target and may have had other 'deals' to get to. Also a white Hyundai sedan.
The guy on the phone did try calling me multiple times in following days, at first agitated and upset because the money had 'left his account'. Even though I had already confirmed with his 'bank' that this was clearly an illegitimate transaction. Cousin - 082 671 0784. Scammer - VUYOLWETHU SHAWN BOYS - 076 431 5611