Medlife — Product Returned but REFUND payment not received

Medicine was purchased on the app on 2nd May and returned on 4th May 2020 - and once the return was made the Medlife app shows the confirmation that the package was picked up - a copy of this is attached

Since then I have been following up with Medlife and they are saying that the case is still in the investigation and are asking me to produce proof of return. Notably, the proof of return is already sent to them from their own App - but they are not accepting this and are asking for a physical document proof - this is absolutely shocking and disgusting.

The amount paid is INR 3995, and this is not small money - on the other hand, the delivery boys are calling and making ruckus discussions and use abusive language, trying to threaten me.