"Over 2 years for an appointment, appalling service"

I have waited 2 years for my next appointment with the dental orthodontics department. After a number of times of emailing & ringing up, no one has responded to my messages or calls. I am disgusted with this level of service and why no one can manage to answer phone calls. I should not have to chase them up for my next appointment, they should have wrote to me letting me know the next steps. Instead I've spent countless hours trying to contact them over the years. I recently had to go down to the hospital to question this & they said someone would get back to me soon. I waited & still no response. So I kept ringing and ringing until I got someone to check what was happening and it turns out they forget out my treatment and being referred to the next department. I am so furious I have had to wait this long for them to sort out my treatment and not letting me be aware. I am yet to receive a letter stating when my next appointment will be. What an awful, poor service.