ask to speak to the insurers dispute resolution officer and lodge your complaints, ask for reference numbers and record who you speak to and what is discussed.
i must stress, try to actually get a resolution. if you cannot get one then you ring the ombudsman
this is ran by the financial services ombusdman, give them your referencenumbers, quite often this will result in another internal person from the insurer (usual Australian and actually employed to resolve the issue) calling you and having another discussion, not sure why the FOS are not helping you, did you ask them who deals with the claim?
i sell automotive insurance in my work, which insurance company are you dealing with here?