Casual staff complaint

I was a casual worker at Mr price home in V&A waterfront in Cape Town. I had signed a contract of 3months which started on the 24th of November 2024 and ended on the 02nd of February 2025. Firstly the money I got paid was not what I signed for which is R30,50 per hour and I worked 8hrs per day for 5 days in a week. Also I was ****** a payment of a week because on week one I worked with no payment then week two I worked again and my money was the amount it was suppose to be. So now when I ask for back payment they tell me that I was payed fully and the is no outstanding amount and I did my calculations and I could see nothing was ending up. For the fact that we were made to work unpaid overtimes without our knowledge is so inhuman. I want help with clarity on this case because I also wanna know what went wrong and why are we not getting paid.