[Resolved]  Delhivery / Ssn Logistics — return pickup lost

Address:

Pune, Maharashtra

I had a return pick up scheduled for one of my online orders. A guy came to my place asking for my return parcel which i handed over. Then next day i received a call from delhivery asking whether they can come pick up the stuff. When i mentioned it has already been picked up they said there could be a duplicate request. Since then we have been trying to track this parcel, in vain, and to figure who came and how he knew i had a return parcel.
They are unable to trace this pick up parcel and i am now at a major loss of money. How will anyone apart from courier service know that i have a pick up?