Dear manager:
I'm so sorry to trouble you in such a busy time,but I do have some complainments about your restaurant.
Yesterday my parents and I had meals in your restaurant,we called a dish which was too salty to eat,and then we were not satisfied with this.However,the waiter there insisted on innocent about the dish and was unfriendly.We strongly appealed to cancel the dish and raise the qualities of the waiters there.We are looking forward to your dealing to this event.
Yours sincerely,XXX