Very disappointed

I opened an account with this sit at the start of the month only to be blocked after an hour because of a self exclusion with a linked account. Which in this case was correct. Only problem I have is that I was allowed to deposit £600 to which £300 is still in there. And not at any point has any money been sent back to me. I have been in contact by phone and sent a lot of messages and I literally have had only one reply in nearly a month. Live chat constantly resets and my messages are always been sent to the relevant team supposedly.feel very disappointed and feel like I have been left in limbo. Thanks