Visit Refused!!!

Today was the day that people from the alternative school were supposed to observe T and M at their current school. We called the school on Monday and told them they were coming. Late in the morning I got a call at work explaining that the principal stopped them at the front desk and refused to let them in the school to observe T and M; saying something about how it was not necessary because they were staying at their current school...? This was all very confusing to all of us. We got a hold of the alternative school on the phone and explained the situation, so they are planning to just visit us at home tomorrow to see T and M and circumvent the school. This is nuts! The current school is acting like they own our kids and that we have no right to make any decisions at all. I also got a call at work and had to go to the school today (the principal was not around at the time) because T was sick. The stress of this teacher and classroom is making him sick regularly now. We have held back until now and tried to be 'nice' to avoid accidentally creating a worse problem for the kids, but I'm pulled out the rest of the stops and had a chat with some influential people that I had avoided involving until now (which of course I am hesitant to name, even indirectly, here), who said they would look into this for me and see what they could do (and they have an interest in resolving this). This is ridiculous and has gone too far.