Complex sentence: Kashyap was already writing the film but Varma felt the need of a much more experienced writer and called Saurabh Shukla to write but Shukla was initially hesitant to do the film since he wrote the films he could direct.
Split into simpler sentences: Kashyap was already writing the film but Varma felt the need of a much more experienced writer for the film. He then called Saurabh Shukla to write but Shukla was initially hesitant to do the film since he wrote the films he could direct.