In a past life, I ran a natural gas retailer. We had 5,000 domestic and commercial customers and it was a profitable little business. Along the way, I picked up a thing or two about consumer behaviour; specifically, they just don't care that much about their power bill.
We made money by enticing new customers with a low offer price or a one-off credit. We'd typically lose money in the first year but reap the rewards if the customer remained with us for several years, which the customer invariably did.
Customers, we understood, believed that all utilities charge about the same, take forever to answer the phone and that switching between one retailer and another wasn't worth the aggravation.
However, the most effective trick up our sleeve was the complexity involved in comparing one utility bill with a competitive one.
A consumer would need 12 months' data, a spreadsheet and a spare couple of hours to make a genuine comparison between the competing offers; taking into account prompt payment discounts and loyalty schemes that abound in a crowded market.