Nothing new, these scammers would definitely do things at all sorts as long they do saw that someone do seek for listing. Checking out emails would really help and in fact
C-cex doesnt really respond thru emails which most likely the one who do contact you is a fake and with that twitter.Hope you didnt able to sent out some BTC or even your own coin.
Just be careful and its good you have spotted it out directly. For exchange matters, i do already treat this exchange as good as dead.