Firstly they told me, that I have withdrawal limit, just 300 usdt, but they will withdraw all my money. After my withdrawal of 300 usdt they've just closed my account. Rest of money was there, That's sad. Don't play there, save your money.
The conversation is not a valid proof but its helpful to understand your case. Your only defense against arbitrage betting accusations is just the sports you made is the largest tennis tournament while arbitrage betting can happened on any type of sports because it only involves the difference on odds of different sportsbook.
As I understand correctly your case, Your account is under the arbitrage restriction which results to hold some of your balance until investigation is done. Just ask them for update regularly about your case. You need to provide screenshots about your conversation and your account balance in the casino. Use talkimage.com to upload picture and share links here.