The Home Information Pack (HIP), which is needed for all homes for sale, includes a certificate showing a property's energy efficiency.


Jennifer Bowring (63), of Main Street, Gedney Dyke, was frustrated that her house was deemed a band F property for energy efficiency – the second highest category.


She pays £720 a year for energy bills yet the report estimates that she should pay £1,300, with a goal of achieving £900 over time.


Mrs Bowring said she has just two non-energy saving bulbs out of 15 in her house.


She said: "I had to pay more than £300 for this report and then they don't take into account your bills but just use their own figures.


"The parameters that they are using are obviously way out."


Mrs Bowring lives at the property with husband Ashley and largely stays at home because she suffers from diabetic neurophy, which makes it difficult for her to walk far.


She said: "I am at home all day and I don't sit in the cold. I have the heaters on but we pay far less than what has been suggested.


"It was quite a shock to see this when you know how much your bills are."


The report is available on the Internet and Mrs Bowring fears it could be used as a bargaining tool when she tries to sell her home to move nearer to Wisbech, where Mr Bowring works.


Vibrant Energy, which carried out the inspection, has been back to re-count the number of energy saving light bulbs.


Operations director Tony Rinaldi said the formula for calculating energy bills, which is used by all companies, makes assumptions based on occupancy and geographical location and does not always match the amounts paid by customers.


He advised Mrs Bowring to take her bills to her estate agent to go with the report to show the discrepancy.