Same situation arised, 16.08.2017 withdraw eth, got the status `completed successfully`and
TXID 0x52be8b2c565692c0ed513643b1c7315c528f0d8be63210ae260da26b2a8111da  -that does not exist in chain!
At once sent mail to Bitfinex support, 11 days passed, and still got no any response from them!