My home phone service is through Comcast and I called them in reference to the calls I have been getting from this same number. She told me that once I hung up with her, I press *60 and it would allow me to enter the phone number for it to be blocked. I'm not sure who your phone service is through but they may offer something like this.
I have telephone service with AT&T and have the call block feature (*60). However, when I tried to block this incoming #, it will not allow me to. I have a feeling this # is behind a PBX and if I could find the # for the PBX, I would be able to block the call.