A parliamentary question at Westminster revealed the number of gas and electricity customers moving suppliers has fallen over recent years.
SNP MP Dr Eilidh Whiteford said prices rose quickly when wholesale prices went up, but fell slowly, if at all, when wholesale prices came down.
She said: “Encouraging customers to switch between energy suppliers has been the UK Government’s answer to tackling the problems of sky high bills, but it is clear this strategy is not working.
“Most people already on a direct debit payment are unlikely to make a significant saving by switching. Indeed, research has shown that many of those who switch have actually ended up on a worse deal.
“Over the summer we saw the big six energy suppliers go through a ‘follow my leader’ of rising energy prices. How is the average consumer supposed to know what is a good deal without knowing when the next company is going to hike prices?”