I don't know HITbtc too much, but I have a dasana account and I haven't used it haha. but is it true that if they delete coins there is no notification?
if it's not there, then the customer's coin will also be lost right? I don't think it's a good policy.
try and ask more about it to hitbtc support, maybe you lack communication, or don't know there is a special notification regarding deletion of coin list.