Enough is enough! You are not asking for any favours! You know all of this... the agent is employed by you,therefore he needs to render a service to you, the client!
Cancel his services (non-existing service) and get in contact with DIAC yourself.
When we started this process, we opted to go solo, not make use of an agent! I never even researched the cost involved for an agent. Do you know why? It is not the migration agent's life, it is YOUR LIFE, he is dealing with! Whether he follows up today or within a week, makes no difference to him, but it makes a huge difference to you. I am sure you get some agents who can be very dedicated to their client... Take things into your own hands! Be your own driver!