One thing I remember being told by my child's behavior specialist is that the different between typical & disabled is often frequency, intensity and/or duration. I'd ask for data on a typical classmate as to how often other students experience the same things.
My thought on advice for the mom: Where do you live? Are you allowed to record a phone call w/o permission of the other party? (Not legal where I live.) You can record calls if this OK where you live since the school seems to not be willing to communicate in writing. If permission is needed, the mom can reply: Please call me after 2 pm. Please be aware that I will be recording this call. Your calling me means that I have your permission to record this call. There are apps on cell phone which will allow calls to be recorded but I'd test them out ahead of time.