Hello thank you for your question.
My name is Tony, and I can assist with this.
You can point out to the energy company that they are not prevented from providing this information to you, as there is an exemption under section 35 of the Data Protection Act 1998 which allows information to be provided/disclosed where there is a need to obtain the information in order to enable you to understand your legal rights and whether you have a cause of action against a third party.
I attach a link to the section here, for your information: http://www.legislation.gov.uk/ukpga/1998/29/section/35
I hope this answers your question, although if not, please feel free to ask me anything else.
If there is nothing more you would like me to answer, please do remember to rate the answer for me. Thank you.