Parliamentary Ombudsman
Your MP can also ask the Parliamentary and Health Service Ombudsman to look into your complaint.
The Ombudsman investigates complaints from members of the public, referred by a Member of Parliament, where they have suffered injustice because of maladministration by Government departments or certain other public bodies. Maladministration generally means poor administration or the wrong application of rules.
The Ombudsman is independent of the Government and is not a civil servant. The Ombudsman is an officer of the House of Commons appointed by the Queen and who reports to Parliament. All complaints are confidential, the investigations are private and there is no charge for the service provided.
You can get more information about the Parliamentary and Health Service
Ombudsman from their website