I called back number (02) 8061 9480 reached IVR of ACM Group debt collector

I returned a missed call from (02) 8061 9480. The operator refused to disclose the name of the organisation or business of the organisation, but wanted both my full name and DOB. As I was unsure if they wanted to contact me as a private citizen or my company, I was happy to provide my name to see if that would identify the reason for my having received this call, but drew the line at DOB given I did not know to whom I was speaking.
Really unprofessional whom every these people are. Recommend do not engage with anyone from this telephone number. If the business need is/was valid, they can email or text.

ACM Group debt collection