apart from the screenshot you shared, would you also mind sharing a screenshot of the conversation with their support?

I visited their thread and from the looks of it, they did say that withdrawals that are "+20mbtc, they need to take time to be sure all plays have been fair", which I assume could take a while.

anyway, just to be clear, you cancelled the pending withdrawal and then played a little and then initiated a withdrawal request again for 15mbtc? if so, you might need to wait for 24-48 hours for it to be approved.