Writing a formal letter is an art because it is in much demand these days. Some examples are official letter format for request sometimes it is official letter format to government, and you may have to write a letter to an organization
COMPLAINT ABOUT NON-COMPLIANCE OF ORDER
You have placed an order for a few books with City Central Book Shop, No. 10, Paharganj, Delhi. You have not received the books so far. Write a letter to the book-shop, complaining about the non-compliance of your order.
Messrs City Central Book
Shop No. 10 Paharganj
I had placed an order for a few books on Physics, Chemistry and English literature. An advance of Rs. 400 was also sent vide draft No. GE 3762 dated 27. 6. 200— drawn on Punjab National Bank, Paharganj, Delhi. But I regret to inform you that it is going to be a month s ince the order was placed. but the books have not been received so far. Kindly send the books at your earliest and inform me from where I should collect the parcel.