1000 EUR payment declined

I won 1000e without bonuses and after wagering my deposit as requested and verifying my account etc., but now the casino is refusing to pay and has declined the payment, accusing me of violating the terms, which I have not done. They have already paid out a sum of 400 without fuss, and nothing has changed in the account after that payment. This is outrageous, and the casino's way of trying to avoid paying the winnings. This is the email I received from them regarding this:

We would like to inform you that your withdrawal has been cancelled by the payments department and the amount of 1,000.01€ has been removed from your balance, due to the breach of the following Terms & Conditions:

12.10 Website reserves the right, in its sole discretion, to void any winnings and forfeit any balance (winnings and deposits) in your betting account, to terminate the Agreement and/or to suspend the provision of the Services or deactivate your account if:

i) we identify you have disguised, or interfered, or taken steps to disguise or interfere, in any way with the IP address of any Device used to access our Site (such as using a Virtual Private Network “VPN”)

ii) it comes to our attention that the customer used forged documents (photos, scanned documents, screenshots, etc.) during the verification procedure or at any point in time the Agreement is active

iii) there is a reasonable suspicion that you have committed or attempted to commit a bonus abuse, either on your own or as part of a group

iv) you are involved in any fraudulent, collusive, fixing, or other unlawful activity in relation to your or third parties’ participation or you use any software-assisted methods or techniques, or hardware devices for your participation in any of the services provided by the Website.

If you have any questions or require further clarification regarding our terms and policies, please do not hesitate to contact our dedicated support team.

I have not violated any of these terms and have already been paid a winning with the same status. Please help me. The casino is stealing my money that I won fair and square. Outrageous!!