My Cryptonator account was protected by 2 factor authentication, performed all recommendations of the service for protection.
Apparently, Cryptonator does not adequately protect the data.

What can be advise in such situation?

Cryptonator has been attacked by hackers a couple of days ago.
Tech Support acknowledged API keys have been stolen so that many of users lost money.
From my account with enabled 2Factor authentication there were stolen 11 BTC.