change the refere for my son,s MN1 application already paid and submitted

I made a mistake in my son,s MN1 application . its says i need a teacher or minister of religion as a refere at least 1 for under 16.but i put two self employed friends as referes. i already paid and submitted the application(can not edited) ,but have not uploaded documents .
Please advise me what to do know

Arrange new referee who has engaged with the child in a professional capacity. Add a cover letter with new referee details on the letter. Get the new referee declaration signed. Upload both with your documents before biometrics.