[Reference: investment company and product number].
I am in dispute with the above investment company, which understand I is authorised by the Financial Conduct Authority.
I have been unable to reach settlement with the company in respect of [describe complaint].
I also understand that the company has now ceased trading [give details of how you found out].
In light of the above I am therefore referring the matter to you.
Please find enclosed copies of all relevant correspondence, and I look forward to hearing from you in due course.