I had my house & contents renewal notice yesterday for £210. I used one of the popular comparison sites using the cover details on the renewal to compare like with like. The exact same company, who I've been with for some years, quoted me on line at £135.
I then had a pop up from the company asking if I wanted to "Live Chat". I explained what I'd done and asked what the reason was. She said she'd look into it. She came back saying on line quotes were often cheaper but it was unusual to get such a large difference in premium. She offered to cancel the £210 renewal price and alter it to £135. Needless to say I accepted.
I did the same thing with the same company for my car insurance in July and saved £35.