How do I complain to Delta? For comments or complaints after your travel experience, you can reach out to Delta Airlines' customer care team by sending them emails or by directly connecting with one of their live human representatives at ???!!???!!???!!???? (OTA) Or Toll-Free 1-888-356-5123 ?(???-????????) [No-Busy Air] Quick Connect.. - to speak about your complaints and concerns. How do I complain to Delta? Following your flight, you can email Delta Airlines' customer service department with any comments or grievances, or