I get abuse from Customers every now and again, trust me they wont do anything about it same as we dont, all the person would have done is hang up then moan to their collegues that you were an arse then prob say that they dont want to speak to you again. TBH if they are a debt agency they will have calls like that all the time - so they prob wont bat an eyelid.

I am assuming you didnt threaten to kill the poor jobsworth?