Seems some job agencies are selling your details to this course provider. When called ask them how they obtained your details (including your name and number).

What was the call regarding? If its for an existing career opportunity, I am interested. If it is for a course I should do to boost my career, I am not interested. Please let me know. Even a text msg will be ok.

I called back number (02) 8080 7312 spoke to a guy who said company name is Careers Australia.