The below given in a sample letter to the post master complaining about the irregular delivery in your locality.
May I draw your kind attention to the irregular delivery of letters in our locality. The postman of the area is negligent in his duty and harasses the residents by keeping back their letters. Sometimes, very important letters are not delivered in time. The other day I received a letter for an interview from a government department. The date of the interview had long since passed when I actually received it.
The postman is not only irregular but also rude to us. Usually he throws the letters in the verandah or hands them to young children. This is highly objectionable. Kindly look into the matter and, if possible, transfer the fellow to some other locality.