River Belle Casino - Self excluded but wont refund deposit

I opened an account at River Belle Casino I've never had an account with them before so assumed I was fine to use it, an hour and a half later after I had made several deposits the account was closed half way though playing. They told me that I had self excluded from a sister casino so I would also need to be self excluded from this casino. I have never received an email or a list of sister sites I wouldn't be able to play at so I was unaware of this. I used all my correct information I didn't use a different name, address or ip address so the system should have picked it up straight away. I've opened accounts in the past with different casinos and I've been locked out before I can even deposit if the account has a self exclusion on it. I feel this should have happened when I opened account with River Belle but instead they let me make several deposits. Today I received a phone call that said the managers reply was I would not be receiving the deposits I made back as I played them. I don't think this is fair as the account was open for ages for me to deposit when I shouldn't have been able to in the first place. I don't understand why we cant come to a mutual agreement they casino doesn't lose any money by returning the deposits and nor do I. I wasn't trying to cheat the system or anything like that I was just unaware of the exclusion on a sister site. I know if I had made a profit on whilst I was playing that they would not pay out any of my winnings and they would only refund the deposits that I made, so why cant they do that as I've made a lost.