"Have you ever called to have your electrical service changed? How was that experience for you? I've had that pleasure, too."
I've done this. It's something the UK seems to be really good at. I checked my annual usage and found the supplier who would charge me the least for that. So I phoned them. That was all I had to do. My bills went down. Fantastic. The UK government seems to be enforcing a competitive market, and I am no fan of the UK government, so this is high praise from me.