Friend had his coins disappear from binance Australia

Just asking for any advice here. I co worker of mine had some coins (several) on binance Australia. Value probably about $5000. He doesn’t check this account often as he was using it as a kind of crypto stash account for the future. He logged back in a couple of months ago and the coins were all gone. He couldn’t even find transaction history for buying the coins. He has contacted binance in regard to this and they also say they can’t see any transaction history. They have made him do a verification of the account by sending his passport saying they would contact him in 72 hours. That was about 2 weeks ago. Any advice appreciated not really sure what happened or what he should do going forward.