He added the poorest and most vulnerable people in society are the "least aware" of discounted energy tariffs available and also the "most likely" to pay using cash, cheque or prepayment meters.
Mr Lishman said: "Energy firms should not have to be dragged unwillingly into addressing the needs of these poorest households - they should show some social awareness.
The attitudes of the energy firms and the "complacency" of industry regulator Ofgem is an outrage, he claimed.
Gavin Brown, the energy spokesman for the Scottish Conservatives, recently said that consumers across the UK are confused about their gas and electricity prices.
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