I will divide your question into two.
With the Immigration and Refugee Board, there must be clear directives from the minister to the chairperson of the board, then to the members of the various divisions of the board, in order to ensure respect both for French and the choice of language of proceedings.
Then, within the department, there must be clear measures to ensure that immigration officers respect the language chosen by claimants, and are held accountable for doing so.
As I mentioned earlier, the only recourse available to a client is to file a complaint with the Commissioner of Official Languages, and we know what can happen then.