Direct TV constantly getting my bill wrong. They will tell you give yo promotion discounts and bill still comes in wrong.

Direct TV is constantly getting my bill wrong. They will tell you they are going to give you a promotion discounts and bill still comes in wrong. Constantly having to call.  Somebody(s) are not doing their job. It is a real hassle. I am real sick and tired of it and may have no choice to cancel even though I have been a customer over 20 years.  It is terrible service!