Category 4 investment firms must promptly acknowledge a customer complaint and in no case, later than within 5 working days of receipt. Licensees must also promptly respond to a customer complaint in accordance with their urgency, and in no case, later than 4 calendar weeks of receiving the complaint, explaining their position and how they propose to deal with the complaint, including any redress. Until the complaint is resolved, the customers must be kept informed of the progress of their complaint.