Inheritance Tax return

Now I am fighting with Corporation Tax refturn due date end May. Top of this , I received inquiry of Inheritance Tax return ,due date June 7. I answered 'Yes, but no guarantee by June 7 ' If you agree with this , I will do may best. Then, I asked him to get all necesarry documents asap. So far after a week after this , I have not receive any docs. How can I do for him to make him happy. If you do for me, I will do for you.