Unfair Gambling facility

I was a happy gambler. I made deposits as per terms of their busness. I was offered a bonus of R20. I did not even use the bonus. I gambled and won R 2500.00. I then wanted to withdraw the money. This goes through a process of verification. After giving them all the documentation they required from me, they rep**** that the money had been taken back by them. The money I won was more than 30% greater than the bonus that they gave me. Now they expect me to be happy with that. What kind of gambling facility are they?