Poor online return customer service

I purchased items online and when I go to the store to return, they advised me that they cannot return my items as the prices are different and I must contact the online store. I contacted the online store (which is a call center in India), I was told that a request needs to be logged for a delivery person to collect my items and I would receive my refund between 3-7 working days. No one has come to collect my items as yet. Why can’t customers just return the item at the store ?