The Tynwald Commissioner for Administration says a Manx Utilities' response to a customer complaint was complacent, dismissive, discourteous and uninformative.
Paul Beckett was asked to investigate after a customer felt their complaint about the organisation's billing hadn't been dealt with properly.
He found a Manx Utilities internal report admitted shortcomings - but said there was a marked difference in tone and content in a letter sent to the complainant.
In a report due to be laid before Tynwald in October, Mr Beckett says a response from an MU director evidences maladministration.
Postal vote applications have to be in soon
Mum launches petition over university support
Bus services north and south face disruption later
Wildlife Trust unveils woodland plans
Deadline looms for by-election nominations
Biker in UK hospital after Mountain crash
Trial event closes roads in Peel and Ramsey
Requisition meeting for Garff voters