Delhivery — Failed to deliver as promised

I have ordered Boat 621 Airdropes in boat official website and paid the amount through online transaction. Using the order no & tracking, I found that the order has reached poonamalle hub on 11th & received in Nanmangalam Delhivery service on 12th morning 6.30pm. But even after getting last checkpoint they failed to deliver or inform me. After sending too many and raising too tickets, they didnt take action. The courier service gave deadline for delivery is 3.00pm of 13th, but they havent. And after 5.30pm just for name sake they transferred out for delivery. I don't know where the product is.