I called back number (08) 8545 1200 rang once then gets disconnected automatically.

saying they are the nab have had about 5 different numbers call and say it was the nab none of them are the nab

Answered the call. It was an automated message saying "This is National Australia Bank. We have an important message for...(My full name)...Please press 1.
When I didn't press 1 it hung up on me.
I have called NAB and they haven't heard of any scam phone calls but said that it wouldn't have been am automated message if it was from them and they would send an email or SMS if they had an important message for me.

Called back twice....both times instantly disconnected. Searching number hasn't shown who they are.

Called number back but call failed