I'm supposed to write a formal letter and I really need help with it. I dont know how to make it the best.

Dear sir

I am writing with regard to the concert that was held at June 15th because I have some complains about it.
Firstly, dancers did not have any chance to join the concert. The information sheet said it would be a concert by performers of all ages and abilities but the dancer had no space to fill in on the sheet.
On the information at the website it was asked after ones level achieved. Why would the school ask that after writing that anyone could join the rehearsals.
Furthermore I have some further complains about the provisional programme. The first half will turn out very boring so why not try to mix the both parts?

The rehearsals between 10-14th June is not long enough before the actual concert . Many people will come very unprepared and many people will get disappointed. They will really high prices for their seats, I believe the prices are actually way to expensive. A student/child should not have to pay ₤9.
The school can raise money in other ways. Have two concerts instead of one - because people wont show up if it is too expensive. I am sure that our school would not want many people to get angry and require their money back. Let us be on the safe side.

Best regards