Start by volunteering in the classroom to helpfully observe. Parents are so quick to send emails, but less likely to put their own time into the situation. Have a parent teacher conference as the next step. If no resolution, then have a parent, teacher, and principal conference. Finally, if you are still not satisfied, then request to change teachers. If this is denied, then file a complaint including all of the steps above.
If we really care about our kids needs, then we need to be more involved in their schooling. Writing a check does not replace volunteering at the school and being present. Many parents don't attend Back to School Night or Open House, but these events are the bare minimum.
Yes, we are all busy, but your child is more important than a few hours at work.