You can complain on Delta's web site and they may compensate you. Compensation is more likely if you are a member of SkyMiles and even more likely if you are an elite (medallion) member. If not a member at all they are unlikely to give you anything. They may give you miles or a voucher. Keep your complaint short and to the point.

If you are a member or plan to begin flying Delta regularly, consider carefully whether this is really worth a complaint and whether it's worth it if $50 is the compensation (and that is the maximum I'd expect). Delta scores its customers on several metrics including whether they complain about little things. If you do, they're going to take you less seriously when you complain about big things.