Amazon India — Haven't received the product but on site it's marked delivered

Address:

Baroda heart hospital, 44 haribhakti colony, near chakli circle, old padra road, Vadodara Gujarat

The order I placed was said to be delivered on Monday dated 15 November, but in real I didn't get any product. Nor was I called by the delivery guy for collecting the product so how could he have delivered the item and marked it delivered without an OTP. When I called the number for asking this the phone number that was provided to me in my email said "the number you are calling does not exist". So what should I consider this. I called customer service several times and everytime they said we'll look into it. But there's no response.