How many movies have Eckart Hachfeld and Ingrid van Bergen collaborated on?

They have worked on 3 movies together! Their first movie together was Der Maulkorb (1958) while their highest rated movie together was Was ist denn bloß mit Willi los? (1970). They have not worked together since Was ist denn bloß mit Willi los? (1970). They are most known for their comedy films together.