Normally I'd agree with you but when it comes to Gas and Electricity all the providers are much of a muchness. The product is identical and the customer service is fairly similar. Even the prices aren't that different.
Agree with this. Given that it's the same product coming through the same cables/pipes, the obvious question is how can one provider offer it cheaper than another? Either they are taking less profit (unlikely) or squeezing their costs, the main ones being labour costs (i.e. having their staff on poorer wages and terms and conditions, or cutting back on customer service). These utilities are natural monopolies, and as such, should be provided by publicly-owned and properly-regulated companies