From experience they have been a pretty decent exchange, i stopped using them though when they discontinued their cloud mining service and their partner GHash.io slowly died down. So haven't been using them for a while now.

But looking at all the threads being opened about cex.io's support, i think that they are indeed scamming or at least having liquidity issues. Perhaps they suffered a hack that was undisclosed or something.

Try to contact support as many times as possible, all you can do at the moment. But others are getting delayed withdrawals as well so it's not you only.