A Bothersome Ex

HOW do you get an Ex to STOP calling you?
It's been over six months since I have had ANY contact of ANY kind with my former FWB.
The last time we spoke, on the phone, I re-iterated what I had already told him in person, which is that he and I are over because I was entering into an actual relationship.

He never wanted an actual relationship and he made that clear right from day one.
I was fine with that as I was still grieving the death of my husband.
We both agreed to be friends with benefits, and that is all.
This lasted over two years, during which time I told him at least four times that one day I would meet someone who wanted to have a relationship with me and our connection would then end.

After I met my new Sweetheart for the first time, and before we became romantically involved, I told my Ex; "this is it. I've met someone special who I intend to see exclusively, so I won't be seeing you any more." He said he understood and he was happy for me.

But now he won't stop calling me and leaving voice mail messages, asking me why I won't return any of his calls!

I refuse to reply or respond to him in any way, because I know him, and I know that any response at all from me would only incourage him more.

I just don't know what part of " I have a new Kingpin" he doesn't get!

XOxo~Drea