This is article from a solid web site will give you the appropriate way to address the letter:
How to Address Church Officials by Fr. William Saunders
What friends and colleagues have told me is that it is important to make it "short, sweet and to the point". What I do is:
- start my initial paragraph with short, brief bullets on why I am writing.
(Ask for something directly, if you want.)
- I then elaborate on the points, and
- finally summarize what I have said.
It can be very difficult at times to go, on and on and on with other issues that bother you.
Try to discipline yourself not to do this. If you have a complaint point, keep it short, very simple and to the point.
We have to remember any Cardinal or bishop is a very busy man with a lot on their plate at any one time. They need our prayers.
In your situation, it's important to remember that all priests are sharers or extensions of the bishops work. If you talk to the bishop personally, and have have issues with your current pastor, the very first thing the bishop will probably ask you, is if you have talked to the priest personally about the issues that concern you, which (I assume) is why you want a new priest.
If you have, you should mention, in the letter, issues you have brought up with him and his replies.
In all the letters I have written to my Cardinal, his secretary or other close associate usually responds for him.
I sense this is a diocesan protocol so don't be disappointed if you don't get a direct personal letter from a Cardinal or bishop, himself.
These are the two I received:
When I share with him my CPATS/AskACatholic.com apostolate.
When I share with him my two new apostolates HelpersOfTheHolySouls.com and BibleBeltCatholics.com.
That's the best I can do for an answer.
Maybe my colleagues have something to say.
Hope this helps,