Gautrain faces possible court action after a man dressed in traditional Ndebele garb was not allowed to board a train because he was not dressed "appropriately".
More than a week ago, Thando Mahlangu was asked to leave the operator's Park Station in Johannesburg.
His lawyer, Benny Buthelezi, told Talk Radio 702's Bongani Bingwa on Thursday that Mahlangu had been humiliated.
He added that "it is a point that needs to be ventilated at the highest level in-country".
During the interview, Buthelezi also accused Gautrain's top management of failing to deal with the issue and of supporting its security guards' decision to bar Mahlangu from boarding a train.
@TheGautrain I'm refused to bought Gautrain from park station to pta because I'm wearing IsiNdebele. I'm wearing my cultural clothing as the results I lost R4500, as I'm late for my appointment. @CyrilRamaphosa @Dailysunsa @EFFSouthAfrica @Julius_S_Malema @tumisole @AdvBarryRoux pic.twitter.com/zGayboJSA9