What do agencies sell?
Digital agencies do not sell. They consult. They search for solutions at the best price according to a (sometimes loosely) defined need. Then they build it keeping in mind quality and innovativeness and of course development time. Production performance itself is a key performance indicator.
Sales, or consulting, is about adapting to the customer needs. This is where lies a big difference in agencies. Some agencies will propose a working model and the customer must adapt their language to fit that model.
Which agency are you?