Caller: Credit Investigation Dept.

I received a call from this no. at 2.45pm today.from a foreign sounding male calling himself Michael?? When I asked if it was a Nuisance Call and why he was calling me..He called me An Idiot can you believe??!!..Then Promptly ended the call..
Naturally I was Furious,,How Dare He?!..
When I tried to call back to complain..The No. was blocked..
I need to know just who these people are!

I called back number 07427 977430 rang once then gets disconnected automatically.