Put in writing your desire to put a good communication process in place between your boy's teacher and the school administration. Ask them to think about the best ways for you to remain in productive communication with you and suggest a few yourself. Tell them you are grateful for the consideration they are giving this matter and that you will be contacting them by phone to set up a brief meeting to put this mutually agreed upon plan into action. Send this letter to the principal and copy his teacher; keep a copy of your letter.
Call within seven to 10 days of when they would have received the letter and set up a time you can all meet. Don't give them the opportunity to come up with times you could never make it; indicate this matter is so important you will take vacation time if necessary to meet with them.
At your meeting, don't be critical about what's happened in the past. Tell them what you need from them in a kind manner and ask them what they need from you. View this as a win-win negotiation. When you've arrived at an agreed upon process of communication, suggest that the process be written up (volunteer to do it if they balk) so everyone has their blueprint to refer to. Express your appreciation for their concern about your son and your family and leave telling them you're looking forward to a fruitful relationship with them.