Who inserts commercials in my Dish Network channels?

I have Dish Network and just about every third commercial these days is advertising a "male enhancement" product of some kind. It is obvious that these commercials are being broadcast over the regular commercials because often I see the last half second of the commercial that was supposed to be broadcast. Is this something Dish Network is doing? Don't the channels that are selling the original commercial time object? How can I get this to stop? I am really getting tired of seeing these things.