rang three times...didn't answer the triple 0 came across as odd

I got an automatic call regarding checking my eligibility to reduce the credit card Interest rates. As soon as I pressed 9 as informed by auto call voice service, I got connected with the Service Rep. He disconnected my line as soon as I asked him the reason of the call. It seems, this fraud service picked my cell phone number to circulate among the telemarketers!!
How do I report this to any concerned authority??