OnePlus India — Need help with exchange of product accidently purchased.

Hi,

I accidently purchased Type C to Type C cable from OnePlus website but I needed USB to Type C cable. Now, I talked to OnePlus customer care executive for the exchange but to my surprise they mentioned that it is not a part of their policy and they cannot exchange the product. This was no where mentioned at the time of purchasing the product, if it is a part of their policy then they should have specifically mentioned "No Exchange" or "No Return" at the time of purchasing the product just like Amazon or Flipkart does.
This is a scam against a customer as the customer only comes to know about their policy once they have purchased the product. I checked OnePlus website and USB to Type C cable also costs the same i.e. Rs:849/-.
Can someone please help me as this is a hard earned money and all I want is a exchange as I have no use of Type C to Type C cable.