Yes, it is definitely confirmed.  86 confirmations so far, 0.023045 BTC:
https://blockchain.info/en/tx/db4c02c63e43a284c4b9dd0ad3206f61ce6f622e825412c8bbc37567485665ca

(you even said it had 73 confirmations in your subject!)

You need to contact their support - looks like there are several ways of doing so on their contact page - this is a problem with their service or their wallet.

There may be a method of exporting the private key from that address if you are using their online wallet or app and importing it using something else (or sweeping).