Have you tried a good chiropractor, applied kinesiologist or massage therapist who understands Hiatal Hernias this problems and knows how to correct it.
There is a self-help adjustment techniques.
Drink a pint of warm water (Body heat) first thing in the morning, then stand on your toes and drop suddenly to your heels several times. The warm water helps to relax the stomach and by dropping down suddenly, the weight of the water nudges the stomach downwards. It may correct a mild case and also help in a more severe case.