Irrelevant information for insurance claim

Hi everyone. I would like some advise on a matter. My late father took out life insurance for us through a broker called PSG consultants. All the relevant medical tests was done upon entry of the life insurance. A year and a half later my dad got ill and was diagnosed with Asbestosis and Mesothelioma. He sadly passed away 3 or 4 months after diagnosis. We submitted The death certificate and the hospital report and filled in all the relevant paperwork. Now they are making us run around for hospital files that was for previous treatment for his back, ears and appendix. Who's responsability is it to carry all these finacial costs of getting these documents and how can they ask for paperwork that is not related to the cause of death. What is my rights here. If I am in the wrong I apologise, but can someone please give me clarity on th subject. Kind regards