The Pennsylvania Public Utility Commission on Thursday reprimanded another competitive electricity supplier for charging customers higher rates than it promised during last year's severe winter.

The PUC voted to fine Stamford, Connecticut-based Public Power L.L.C. $72,000 for overcharging about 50 customers whose variable rates it had promised would not go up by more than 15 percent. The company said its new owners, Crius Energy, had discontinued the price-protection plan and that it had failed to recognize existing customers on the plan, resulting in the billing errors.

The company last year refunded $6,558 to the customers for 119 instances of overcharging, according to the PUC.

Public Power is the latest of the unfinished list of suppliers to get penalized for violating utility regulations during the polar vortex, when many variable-rate customers got hit with dramatic increases in energy prices. "I know there's more of these on the horizon," said Commissioner Robert F. Powelson.

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