Zomato Canceled My Dinner Order and Refused to Refund or Redeliver

Using Zomato, I placed supper orders for my family expecting it to show up at the designated hour. The delivery time changed from 20 minutes to 15 minutes and so on after waiting almost two hours. Concerned, I phoned the delivery executive to find out that I apparently did not answer their calls, hence my order had been cancelled over one hour ago. This was unexpected since I carried my phone with me all through and never missed any calls. I got right on calling Zomato's customer care and sent images of my call record proving no attempts to get in touch. This proof notwithstanding, they refused to redeliver the order or refund me. Paying the whole cost for an undelivery order and then being held responsible for their error is unacceptable.