The agent is a professional, and if the above events occur, the agent qualification will be revoked. I think at least I won't take such a big risk to do such a thing.
From the perspective of maximizing your interests, the Patent Office will usually advise you to entrust an agency, and an experienced agent can give you great help in the process of writing patent documents, replying to examination opinions and authorizing. So you need to make some efforts to determine the firm in the early stage, but once it is determined, it is necessary to use people without doubt.