A new poll by the Association of Convenience Stores (ACS) reveals that one in five independent retailers receives inadequate notice that their energy contract is about to end.
One in 10 have received back-dated bills and one in four businesses have been initially offered unfavourable renewal terms on their energy contract.
Earlier this year the regulator said it would consider banning such clauses for micro businesses, which would have prevented smaller c-stores from being locked into paying a higher tariff for a fixed term.
It now says it will allow the practice to continue, with energy companies cleared to participate in contract rolling for up to a year on the grounds that 'out of contract' charges for businesses which did not renegotiate their deal would be even more severe.
ACS chief executive James Lowman said: "Thousands of small retail businesses are suffering under these tactics. We need Ofgem to revert to its decision to stop rolling contracts."
Lowman added: "We want businesses to be given more flexibility to switch energy companies if they find themselves in this situation. If energy companies have competitive deals and good practice then there will be no problem."
ACS is calling on retailers to tell the regulator their views. It suggests that if Ofgem is unable to regulate the power suppliers, the market should be referred to the Competition Commission for a thorough inquiry.