Refuse to pay wages

My 2 brothers aged 15 and 16 were hired to work during the December holidays 2016 by Mr Naicker on behalf of Grid group to watch as security guards the equipment used to construct one of the buildings being built in riverhorse valley.they worked 7 days a week including holidays from the 17-12-2015 to 11-01-2016 days promised to earn R100 a day,all they ever got paid was R500 after me calling Me Naicker asking him when he will pay them.ever since he has been giving them a tu around for their R2100 still owed to them and the excuse he has being giving them is that Grid has not paid him.It pains me to see this happen as this was their first ever holiday job and had sacrificed their time hoping they will get paid so they can use the cash as pocket money when going back to school. Every Thursday thru call him and tells them will pay them the next day, the boys wait for him at the site and he never shows up,This is cruel and coming from such a big and reputable company such as The Grid group.How dare they exploit Young children trying to be decent people, instead of spending time on the street taking drugs and crime, they opted to get a job I'm devasted and angry.someone Help