It looks like you violated their Terms of Service. Did you have more than one account?
It’s not about having multiple accounts alone that cause him violation of ToS. The support statement is referring that they will do the same in case this user has more account that will the same activity that violates the ToS.
Probably it involves arbitrage betting while availing the casino bonuses since this the popular trick of users that want to take advantage from casino offers promotion.
There’s no way to solve this unless OP is honest on his statement and avail the service of CG or AG.
I think you need to read the description carefully, that I only played with my own money, and I didn't use any bonuses, and I lost my first deposit, which they didn't refund. I'm glad you're trying to protect the casino, but this casino is just a scam
For me it is unclear which rule of the casino you violeted. Could you specify it?