spam - blocking

Caller: Ben

Firstly I had (03) 9912 4874 call and I answered by saying my name but person hung up. When I attempted to call back it said the mobile phone has been disconnected.
Then 19 minutes later (03) 9912 4874 called and it was Ben. Foreign accent talking with an echo of my voice in the call. Ben wanted to talk about financial market and referring to Amazon. Said he wasn’t selling anything but educates people in financial markets.
I hung up the call at this and then blocked both numbers on my phone.

i am so fed up with these calls - even when you block the numbers it keeps ringing

I called back the number (03) 9912 4877 but was routed automatically to an ivr

Number identified as spam.