If when you write a letter to an admin it comes across as a personal attack upon the centre or themselves it will not produce the results you are looking for. Although you might have no such intention what you have written could nevertheless come across that way because of the wording.
As a human being it is difficult to take criticism. The worldly reaction is that it makes us raw, sensitive, paranoid, defensive and we retreat into a little shell when we sit trying to reassure ourselves that our critique is wrong, calling upon our friends to reassure us that our 'attacker' doest know what they are talking about, is irrational and should be ignored or even shunned.
This is our basic human reaction and it not a crime. But in Buddhist philosophy it is considered a deluded reaction. Nevertheless people will revert to it if they have a lot of work on and are regularly being criticised. This is the position of the person you are writing to. If they have a certain way of doing things that is leading to widespread criticism of their administrative techniques then it is a bad situation for them because they will be suffering a regular & consistent character assassination. Therefore to write a letter saying you have offended me & are doing a bad job wont break this cycle of events.
If we are compassionate Mahayanists we will write a letter saying that they as an admin are needlessly suffering and that we appreciate that they are trying to do a very difficult job. Then we can explain that although its hard to do the job perfectly & keep everybody happy one or two things we feel are leading to misunderstandings friction & if they try method 'b' (with you describing it) then the upset people might stop misunderstanding & getting upset. Then people will be more harmonious with the admins & your job as an admin will become much more comfortable & pleasant ...which is of course a good result.
Of course this article is open to debate & will be modified in accordance with feedback given. If you have written any examples of a good letter I would be happy to publish them as an open letter on the condition that they follow the terms described in the comments feature. These are that the letter is:
-General IE not going into details that give names of places or people
-Constructive with a plausible solution presented that would not cause offence.
The main point is if you manage to avoid anger & write good letters repeatedly then the obstacle is overcome. But the obstacle will not be overcome if you write a letter which is insulting, impractical, dictatorial (dishing out orders), juggling philosophy points, talking in riddles or poems, judgemental, long winded, deconstructive, destructive, endlessly negative or all about you & how emotional you are.