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.