"Wording of your appointment letter"

My teenage son has just received a first appointment letter for physiotherapy. Is it necessary for the letter to have such a threatening tone? "If you do not attend this appointment, you may be discharged from the Service and your GP will be informed of your non-attendance." What on earth is this about? We would never miss a medical appointment and I don't want to receive a letter implying that we would. I am not surprised that such a letter was not signed by one of your staff. Please re-consider your approach and treat patients with more respect. We all lead busy lives and some of us are organised.