DTDC Courier & Cargo — shipment undelivered 5 days after reaching my city. no ownership from customer-service even after dozens of calls to report the issue

My package shipped from delhi to chennai on aug 12th. It has been 5 days since then and the package is still undelivered. It was showing rerouted to a different distribution center. I called customer-service at least a dozen times since last 5 days. They keep assuring me the package will be delivered but there is no progress. No one is contacting me to give me an update. This is very poor customer-service from a company whose tagline is "most preferred courier company in india".