I need some advise please. 

My employer has not given us a proper increase in 2 years. 

Last year when Covid hit we didnt get anything (Covid hit in March, increase due in April) - we understood this and my employer said he will review the situation in a few months and revert back to us. When we asked a few months later it was denied even though he was doing good financially in his practice. This year we got offered 3.5% increase, when disputed he raised it to 4.25, with no discussion further. Basically just a take it or leave it approach. His practice is doing very good financially, but apparently he cannot afford the 7.8% we asked (as to make up for last year + this year). 

At the same time of him not being able to afford 7.8% (which equals to R1000 on my salary) he bought his son a R380k bakkie (and declared it as a work bakkie + employed his son at R4500p/m as a courier). The son uses the bakkie as personal use and he does not do any delivery/courier of any items. His daughter was also employed at R4500p/m, but also does not work in the practice. 

So in the month of 'not being able to afford our increases' he employed his children at R4500 p/m each in the practice, but they do not work here. 

I would like to get some legal advise regarding this. 

I am the only breadwinner in my family as my husband lost his job due to covid and this feels like unfair labour practice and nepotism to me.