Ms Stuart found one example in local resident Stephanie Langdell, who pays between £5 and £7 a day to heat and light her small flat with a prepayment meter.
This figure is "well in excess" of what Direct Debit customers would pay for the same gas and electricity.
Ms Stuart said: "It is wholly wrong for the energy companies to exploit these people by expecting them to pay far more than their other customers.
"That's why I am asking the government to step in and force them to act. Enough is enough."
The European Union's (EU) commissioner of consumer affairs Maglena Kuneva recently announced she would be looking into the price of electricity in all 27 EU stated so analyse if consumers are getting a fair deal.
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