Unfortunately, this is something that does occur from time to time and this is addressed within our Rules page on the Cool Cat website (in the General Terms section):
'Some of our processors pre-approve transactions and then process the transactions in a batch process later. If your transaction happens to be declined at that time of it being processed, and if there are winnings generated from your pre-approved deposit, winnings from that transaction will become void.'
I can assure you this is not some sort of tactic to cheat you out of a withdrawal. If you look around the AskGamblers website, you'll see I'm dealing with players owed tens of thousands of dollars. Knowing this, does it stand to reason we'd use something like this against you with a $550 withdrawal as opposed to someone owed $50,000? This is just one of those unfortunate things that occurs--most likely your bank declined the purchase after the initial pre-approval on our processor's end.
If you check your bank statement and find that there are indeed two $30 payments (you'll need to look for April 27th--possibly April 28th, as you're in the UK), please forward the complete statement to the email address you already have for me. If these payments are showing, I will pass this on to our Payments Manager for further investigation. If your statement does not show the payments (which I suspect they don't), there is nothing further I'll be able to do on this.
I genuinely understand your frustration and disappointment for this.
I'll look forward to hearing from you,