We have recently had to renew our home insurance policy. We have been with Direct Line for more than 8 years, and they have always sent us an automatic renewal notice, which we have until this year just gone along with: at the renewal date they will debit your renewal fee, and that's that... nice and easy.
(our excuse being that renewal is due just before we are leaving on holidays etc etc)
Yeah right. Until we received a door-to-door flyer stating that they could insure a household like ours for £400 less than what we had been quoted. We called their customer services team to ask about the huge difference. They had a lame excuse that of course our quote did not include the 8 year no claims discount.. 
All of a sudden the quote was £200 less than the amount that they were automatically going to debit our account with. 
.
We have always considered ourselves reasonably up to speed with the price comparison websites, LOOOOOOVE meerkats and opera etc 
, but have now realised that we probably were overcharged last year too. I got a customer satisfaction email today and have told them exactly this.
At least we found out in time, and I thought I'd warn you all to check before you renew ...