Dont know this number but recived a call

My phone read "suspected spam" so I didn't answer & flicked it thru to message bank. No voicemail left as usual again as I've gotten a couple of calls from this number & they never leave a message. Probably spam!

Called earlier today but I missed the call. About an hour later I get a call from another number but only difference is 1 digit. Robo voice telling me there is a transaction of $1800 against my Commonwealth Bank credit card, wanting me to press 1 for non approval or 2 of approval (or something similar). Obviously a scam. I didn't press any numbers but stayed on the line and it soon after automatically hung up the call.