Well, that's your answer then. There is no point sending them more emails or support tickets - you will just have to wait for them to complete their "compliance review". Unfortunately, centralized exchanges spring this kind of behavior on their customers all the time - they let you deposit, let you trade, but then as soon as you try to actually withdraw your money from their platform, suddenly there is something suspicious about your activity and they need more information. Have you deposited or tried to withdraw to somewhere like a casino, betting site, or a mixer? Often exchanges will flag you up for that. If you haven't completed KYC yet at Cex, then I would expect that they are going to ask you to, and you will have to decide whether to give up your personal information or lose access to your coins.

Even without using fiat, centralized exchanges still like to police their customers and decide what you are allowed to do with your money. To avoid situations like this, I solely use decentralized exchanges.