Yes and also ones of complaint....I'm still with the surgery ( sometimes unfortunately!) but I think if the need is there to put things in writing then it should be done 'in the nicest possible way' of course. Hope you do what you feel is needed and it turns out well.
Sometimes a letter is easier to lay out than a hurried phone call when you don't always get to speak to the person you want - these days I'd just make an appointment and talk it through often talking a written list of notes so nothing got missed.