Caller: "James Smith"

They say they're from CBA and that they're following up a scam transaction of about $800 to a charity attempted somewhere in Victoria. They ask you to log on your CBA app and verify if any other transactions are showing that weren't made by you. When I checked my CBA app I told him there are no transactions of $800, they advised that they "blocked the transaction and called me because if it..." They then ask you to download "TeamViewer QuickSupport" and ask for the screen-share code and for you to start "broadcasting".... He then wanted to give me a code or a reference of some sorts and mentioned that I'd give that to CBA's security department.
The whole call at first could possibly be legit, but started to feel weirder and weirder. I stopped broadcasting immediately and when I pressed for a name they were very hesitant and ended up giving the fakest name possible: James Smith... or when I asked for a CBA employee reference they became impatient and told me I could call CBA myself and hung up. Called CBA immediately after.
I called back this number and a gentleman who is not called James Smith picked up. I told him I had a missed call from this number and he implied he didn't know anything about it.