"Never got back to me"

After visiting the dermatology's department at Guy's hospital, I received a letter with the outcome of the tests (not the actual results) and the diagnosis explaining that the reason of my problem is not clear and that further testing needs to be done. The hospital never contacted me for arranging my next appointment instead I had to call and ask them to arrange an appointment. When the appointment was arranged and I received the letter detailing the appointment details, I called back to the hospital department to change the time of the appointment. The lady I spoke to instead of changing the time of the appointment only, also changed the date which then resulted in having my appointment 1 month later. When I noticed the date change it was too late and due to being unable to make it on the new date I had to move the appointment forward by 2 months. I have visited the clinic middle of September and my next appointment is in middle of April (7 months later). This is very disappointing and frustrating and the worse part is that there is nothing you can do about it. Unfortunately the NHS system cannot respond to its patients' demands.