https://cointelegraph.com/news/exchange-demands-users-return-bitcoin-bought-for-6k-during-tech-glitch?utm_source=Telegram&utm_medium=social

Their statement:
“It’s very understandable that a lot of users will feel upset they were able to buy what they thought an order was there for Bitcoin at very low prices. But unfortunately, the underlying Bitcoins were never in the possession of the exchange, so there’s never really anything there to be bought or sold.”

If they're selling BTC that is not in their possession, then their exchange is a Scam/Fraud (inflating what not really in their exchange).
If some endusers were able to transfer btc to their personal wallet, then the statement isn't true. You can't fake a bitcoin that gets transferred to your wallet.

This should be thoroughly investigated and audited by BSP and SEC. How much crypto does PDAX really have in their possession?