In two media reports, one by micky.com.au, and the other by finder; it has been reported that the exchange "myCryptoWallet" has had its account frozen by National Australia Bank, which is one of Australia's "Big4" banks.
The exchange has threatened legal action against the bank, citing that it will claim for damages and "gross negligence.
As someone who has been fairly well aware of the Australian crypto market, I had not heard of this particular exchange / marketplace, and do not know anyone personally impacted by these dealings. Both sources quote an e-mail sent by myCryptoWallet to its users:
Due to National Australia Bank (NAB) closing our bank account without notice, we are sorry to inform you that all withdrawals are currently disabled until further notice. This does not affect deposits as we have opened a separate bank account to handle any future deposits.
As with most exchanges of this nature, users do not own their private keys, which in essence means that they don't own their funds directly.
If you're purchasing any cryptocurrency from a centralised exchange, you should always move funds to a wallet where you control the private keys.
This is not the first time an Australian bank has closed a crypto-currency bridge, or exchange down without warning. Some years ago, btc-markets had to change its banking provider after it had its accounts shut down by its bank.
If you're a victim of the myCryptoWallet shutdown, there are alternatives, such as BTC Markets who trade in BTC, LTC, ETH, ETC, XRP, PWR, BCHABC and BCHSV, and the popular Coinspot, which trades in a larger number of currencies.
As always, be safe with your assets, especially your crypto!