Caller: Allegedly CBA security

Call connected and I was advised suspected overseas transaction on by CBA account. Advised $800 transferred to a person in the UK with the name of "can't recall" and asked if I had authorised. Said no and was advised likely that hackers had got into my device and that I should go into Google from that device and enter an IP address etc and this would block the hacker. I advised that I would not do that and I asked for her phone number and details so I could validate with the bank. She abruptly handed me over to a male who was quite insistent that I follow the approach and my money was at risk etc. Gave me a supposed employee number and his name John Stewart (this was clearly a fake name based on his non-English accent). I said I would look into and call them back (which I never did). But I did call CBA who confirmed that no-one had called and there was no such activity on my account. Be aware folks.