read RPS first
https://spada.uns.ac.id/pluginfile.php/144686/mod_resource/intro/RPS%20BEW%202020.pdf
Introduction to Business Correspondence
Structure and presentation of business content and style
Enquiries
Replies and quotations
Letters for ordering
Letters for payment
Letter for complaining
Letter for adjustment
Letter for credit
Doing Banking in Bussines
Handling Agents and agencies
Handling transportation and shipping