Casino Forum Uk

I am based in the UK and opened an account with ' Big Ben Slots ' who are part of the Jumpman Gaming Network.
I deposited £400 and won £1500 - after much deliberation / asking for all documents/copy of bank statements etc they ' verified ' my account and paid me my winnings - it was a very long process.
I then deposited a further £400 , won just over £1600 and they then promptly closed my account and returned my deposit !!!!
Of course, I quickly emailed them to ask what was going on and I was told my account was under ' review '.
Over the course of the next 6 - 8 weeks, I was to supply time and time again some incredibly intrusive information regarding my bank account payments - these ranged from the ridiculous - ' can you tell us what the payment to ' Barclaycard ' is (!!) 'to the reason I paid cash into my bank account.
I am a self-employed Art Dealer and I was asked to supply bank statements for both my personal AND business account which I did and was again asked the background for around 30 transactions.
After approximately 8 weeks of going back and forth I was told because I didn't have an invoice for a cash transaction that was paid into my account they were not going to reopen my account or indeed pay me !!!! What a fantastic business model ?? You let your players deposit ( I assume I could have lost tens of thousands and it wouldn't have been a problem ) and then if they win - ask for a load of documentation to find any excuse, not to payout !!!
I assume that if I had lost say £10K then the fact that I didn't have an invoice for my cash transaction would of not have been a problem (??) and of course, they had already paid me once !!!
Can they really do this ??
Surely these companies are just using the ' KYC ' rules as an instrument to refuse / delay payments ???
If any company doesn't want to deal with a customer that's fine but surely they should not allow customers to deposit in the meantime - to ask for all this information AFTER you have deposited and won and then not pay out is surely theft >>
Has anyone else in the UK had a similar experience ??
Any help anyone could give me I woudl be most grateful - many thanks indeed,