If you don't mind could either of you also inform us when the issue gets resolved because i am assuming it didn't get resolved. I don't have currently any money in CEX.io but i have an account in there and depending on the time this gets resolved affects if i want to use their service in the future.
Both of them (CEX representative and OP) has been offline for a few days now, I think you will need to wait for a while until this gets resolved (if it ever will). Why don't you move to other services in the first place? I don't think there is a need to stick with CEX.IO since you have no money there.
If you want to trade your BTC for altcoin there are tons of options out there. If I remember correctly some members mention Kucoin if no KYC is what you're looking for. It still works but don't expect it to last forever. If fiat is what you're looking for you can also use dex. Just a little bit complicated but should give you better control over your money.
We know that there are some platforms which doesnt list out a specific coin and this is why people do end up on dealing with platforms which arent supposed to be deal off with.
Speaking about in between negotiations between op and cex representative, then we dont know if the problem had already got resolved or not.
One of the things i do really get worried about when depositing huge amounts of money on any centralized platform is that they could potentially
hold it up and say some issues which is bullshit actually.