My first suggestion would be to discern what type of Montessori school your school is. Some independent schools remain independent for specific reasons. Others simply don't meet the standards. Parents should be aware of and comfortable with the school's position and philosophy. Above all, the school has to match your desires and interpretation of Montessori education.
Parents know what's right for their child.
Every Montessori course I am familiar with are one to two years in length. You are paying the tuition for a Montessori education program and have every right to expect that a school that presents itself as a Montessori school is just that. A quality Montessori program has to begin with appropriately train teachers. I would suggest that you go the Montessori School Accreditation Commission and review their standards for schools. They are a new program that will provide accreditation for Montessori schools.