This is a question advertising agencies have been asked with increasing frequency in recent years. The question has been debated, and the introspection is still on. It's not easy for established agencies, accustomed to a way of working to change the manner in which they earn their revenues.
New agencies are more willing to experiment.
Here's one that has done it, and seems to be succeeding. According to its directors, and is looking forward to rapid growth. One day they decided to do it on their own, their own way. They're talking of accountability. Both Vakeel and Raj feel that a fee-based system makes it easier for them to have dispassionate advice accepted by dispassionate clients, and helps them achieve accountable results.