Energy regulator Ofgem is urging the government to give it the power to protect firms from what it calls rogue brokers, mis-selling energy deals.
Its research found that between 14% and 17% of businesses which had used brokers were not satisfied with them.
They were concerned about cold calling, high-pressure sales tactics and unprofessional behaviour from brokers.
Citizens Advice said 42% of complaints it received from small businesses about mis-selling had mentioned brokers.
Ofgem spokesman Mark Wiltsher told the BBC: "We've had quite outrageous behaviour; sometimes energy brokers have phoned up impersonating another company, to try and get an energy company switch, and also we've had brokers telling a company 'You'll get a cheaper deal', and once they sign up, they find out they are paying more for their energy."