The hearing, conducted by an independent disciplinary committee, will take place on or before Tuesday, 19 May.
But with Middlesbrough not allowed to be present, they are calling on the EFL to expel Southampton from the play-offs in the interests of fairness and to deter clubs from trying anything similar in future.
The statement added: “We remain hopeful that the EFL, as regulator, will pursue such a sanction to protect the integrity of the game, safeguard all member clubs, and deter any attempt in the future to obtain an unfair and unlawful advantage in pursuit of promotion to the Premier League.”