When I was a mere Coglet, two of my formative clients were Kellogg's and VW. It would be hard to pick two better clients to grow up with. Kellogg brand managers back then were given a book on working with their advertising agencies, what was expected of them, their areas of responsibility and so on. The first sentence on the first page read something like this: "It is not your job to change the advertising agency. It is your job to work with the agency, to get the most from the agency."