Scam calls after setting up appointment

As the title says, I'm getting scam calls from an 855 phone number after talking to tech support & since they couldn't resolve my issue they schedule someone to come to my home. Made an appointment last week for a tech to come out Friday to see if they can find out what's causing the problem, within 30 minutes I received a call claiming to be Comcast, I nearly fell for it but my gut said not to give any personal info. I told him I wasn't authorized to give him any info & refused to give my name. After I hung up I googled the number & saw it definitely is a scam. 

The issue still isn't resolved a week later, I called & spoke with a tech for over 2 hours trying to see if they could help, but they couldn't & again, set up an appointment to come out. Again... I received a call from the same 855 number (I'm not sure how they're getting through as I have the number blocked). I told him I didn't have time for his scam call, he ignored what I said & continued to try to give me his nonsense. 

I want to know how & why it's getting "leaked" to these scammers we have technicians coming to the house. Is Comcast selling our info & phone numbers? This should NOT be happening.