My payments are getting later and are reducing

Over the past few months I have had problems with the csa. Infact for years. Over the past few months my payments have been later and later. Yet agin I havnt received this months payment. I have also had problems with my payments being reduced so much that over the past year, and a half it has been dropped almost £100. I am tired of trying to get to the bottom of this. as I am just ignored.