Physical assault for no reason by Bouncers outside

Hi, My son and his friends went to Presleys Boksburg on Saturday. Firstly the alcohol they serve there are mixed left overs making the kids exceptionally drunk and disorientated. This should be investigated. Secondly my son was taken out of the club and into the parking lot and beaten by two bouncers a black and a white guy for no reason. Last time I checked bouncers only make sure people arguing inside are taken outside not taken into the parking lot and being sit on and being beaten repeatedly. We are opening a case of assault with SAP but the SAP seems to be not to phased about these incidents and the SAP and bouncers have each others backs what do we do?