I am with EON
Had the smart meters fitted (after 2 attemps) a few years ago Novelty of monitoring usage wore off after a week or so. 
Before christmas they said they had a problem with the smart reader readings but was now sorted, shortly after I recieved an email saying how regular I could have the system monited, 15 mins, hourly, daily etc
So why are they still sending estimated bills? 
Also now they are not sending meter readers out what happened to inspecing the meters etc. I was told by EON that by law they have to inspect the equipment every 2 years.
Because they can then systematically over charge you, and invest the over payments into any investments of their choosing and credit you the difference if you notice/kick off.
If you think that's unrealistic... Say they have three million customers and they overcharged everyone by a mere £5 a month, that's £15,000,000 a month that they can get 10-15% return on. And the credits you might get back actually cost them nothing because they're already being paid to produce the energy and they can write the credits off against taxes.
The actual number is probably twenty times that, and you can guarantee that they are all at it

And if they're savvy, they will also be putting some of that money into renewable schemes with government subsidies and rebates and doubling their money...