I can see having these problems in public schools, but your are paying them. Why all the secrets? Why are they not forthcoming with information? The school should send home a MAP report each time your child takes the test (which in most districts is a minimum of 2 times a year). NWEA (the company that does the MAP test) creates a Student Progress Report and I get it each time my child takes the MAP. It is an especially useful tool to monitor your child's growth. I would suspect that your child is in the 99% above his grade level. The MAP score is based on a RIT number that correspondence to a %. So, if you can get his RIT, you can go to the NWEA website and get the conversion chart and see for yourself.
