Ecom Express has to be by far the WORST courier company I've seen in my life so far. They delay the shipments and don't even bother to respond to customer emails. Their customer support phone number is useless, it's an IVR where you'd be told when your package was 'Supposed' to be delivered. There is no option to talk to a support agent or to lodge a complaint.
Would also courier aggregators like #Shiprocket to remove Ecom Express from their list of couriers.