Is it true that once I apply through one agent for a New Zealand university, I cannot change agents for the visa process?

No, you can change your agent during the New Zealand university application process, including the visa stage. The process and requirements depend on the university.

Some universities, like the University of Auckland, require a 'Change of Agent' form signed by both your current and new agents and submitted to their International Office.

Policies may vary, and approval is at the university’s discretion. Contact your university’s International Office to confirm their specific process for changing agents.