If a company you did business with forges your signature for having a new contract what can be done for that?

my contract with a utility company was over and the company changed names. The new company insisted that I had renewed it and even signed the contract. The signature was not even mine and nor was it any of my family. They wanted to penalize me for not agreeing to be with them. What can be done to this company as I don't want it to happen to others and because its a fraud, is the company not liable for the fraud of the staff member that did put my name as a signature?