We understand that players value transparency, and we always provide an opportunity for further clarification. If the player disagrees with our decision, they are free to escalate the case through independent third-party mediation services such as AskGamblers or Casino Guru. We are fully prepared to present all the evidence supporting our findings through these platforms.
The player has already lost his funds by cancelling the withdrawal and placing bets with that. Therefore, it doesn't matter anymore whether OP agree or disagree with your decision. It would have been better if your support team had said about this to him earlier.
Also, you shouldn't allow the users to cancel their withdrawal in this type of situation. There would have been a chance of getting the refund of the deposit if OP hadn't lost his account balance by cancelling the withdrawal.