Cashing out

I should be giving them a zero..I won on free 30 spins from Mega Drums I played the Playthrough and after that i won R1200..I cashed it out then I received an email from Duke Harvey saying that I must deposit so that my winnings can be paid out I deposited R100...when I ask the customer care services they are saying that I am only eligable to get R500 😏....where is the rest of my winnings mxm I sear to god this Casino should be closed down they are ****mers