Really frightening message from Trustpilot:

"I wanted to inquire something, so I went to visit their office ("2nd Floor, 1-5 Clerkenwell Road, London, EC1M 5PA, United Kingdom" on their website) only to find that there was NO CEX OFFICE there. I thus asked the businesses on that specific floor on that address, and they said that they've never heard of Cex.Io, however, another person came looking for them before and also couldn't find them.

Long story short, the address they have is fake. They do not have a physical office and no one at that address has heard of them. This is very suspicious, and I thus decided not to deal with them. It's good that I didn't as many people seem to be struggling to withdraw money from them (they have a dodgy system where you can buy bitcoin without verification, but can only withdraw with verification, and seem to be refusing verification of accounts.)."