If you need to modify your delivery but your package is already en route, you should contact the appropriate customer support for your shipping carrier. For packages shipped via UPS, you can call 1-800-742-5877 with your tracking number to make adjustments. For FedEx packages, you can call 1-800-463-3339 with your tracking number. If your package is being shipped through USPS, you can call 1-800-275-8777 with your tracking number.