I received a similar crazy call from my exAH about 10 years ago. I did not know who it was on my office phone, only that the call was coming in from Maryland.
My exAH started talking in major panic-mode. He needed a favor. He desperately needed money NOW. He was short of cash. Blah, blah, blah. And he acted as if I was going to toss more money at him, after the thousands I'd doled out to keep us afloat all the times he was gainfully unemployed.
I actually listened, as you did, for a few minutes. My ex also could not understand why I wouldn't just pony up a few bucks to get him out of another jam.
I told him where he could shove his idea and hung up on him. He never called me at work to ask for money again. Although he did have the nerve to call one time to ask for one of my recipes he loved because he and his "live-in honey" were throwing a dinner party. Jeesh!
Believe me, kj, I understand your feelings of discomfort. It's like talking to somebody who has no conscience .... a sociopath. And that always made me uncomfortable about my ex. It was also his sense of entitlement; I OWED him. Crazy, but true.
Like sailorjohn said, if your ex calls again, just hang up on him. As for my home phone, I had the number changed to unlisted and unpublished. I also changed my cell number. I even got rid of my email address and set up a new one.
If you feel you are being harrassed or stalked, perhaps you may want to give the police a call to see if they have any other suggestions.