Shed some light on minimum wage

CAN responsible authorities make it clear on the correct amount of pay someone should be getting?
Diploma and degree holders should be different from common labourers.
Some companies are paying K3.50/hour for diploma and degree holders on probation and only a minimum of 10toea increase after probation.
After another six months they offer another 10toea increase even though we have worked hard to earn a good evaluation from supervisors. This is hard as months go by, our family are suffering and we cannot even accomplish monthly and yearly goals.
Can responsible authorities look into this?
Also provide information on the correct amount of payment.