Since there is little information for me to go on here, I'll try to respond in general terms.
I realize it is the end of the school year for most students, but if this type of a situation happens again, here are a few things you can do.
Document. Clearly state what your child is having difficulty with. If there is an academic or behavioral plan, make sure everyone has a copy and is following through with it. Keep a journal listing the facts (not your opinions) about what happened. This could be a record of phone calls or conversations you had in when dropping off or picking up your child. Make copies of the notes you sent to the teachers and file the responses with the corresponding note. If there is any of your child's work at backs up what you have questioned, keep that as well.
Conference. Set up regular conferences with the teacher. If you feel you are not being heard, request the team leader or department head to be in attendance. Go in with a list of concerns (try not to get emotional) and don't be afraid to ask lots of questions. Good teachers will take the time to explain and to try to work with you. If the teacher asks you for assistance, follow through. What I mean by that is, if the classroom teacher says your child needs to practice reading at home, or needs to memorize the times tables, then do it. You need to work together.
Involve the Administration, Guidance Counselor, Reading Coach. If things aren't going well, request a meeting with someone higher up than the teacher. If your points a valid, these people can step in and help.
Stay Involved. If you can, volunteer. There is nothing like watching the teacher and for that matter your child in action. This might shed a different perspective on the situation. If you can't be there on a regular basis, stay in touch with the teacher as much as possible whether by note, email or phone call.
Because I don't know the detail, hopefully something I have mentioned will help or at least spark an idea. Good luck.