I wish I could find it, there is a website where people who are harassed by phone calls can compare notes - I did it when I kept getting calls and I found that hundreds of other people were doing so, too. That's when I joined Call Preference Service and it's nearly all stopped - no more cold calling.
I had a phone call from EDF last night, I suspect they wanted to sell me gas, but when the chap asked me to confirm my address, and I told him that if they'd got my name and knew I have my electricity from them, and I was receiving bills OK so they already knew my address, he terminated the call.
I'll keep looking for that website.