Myntra.com — delivery partner misbehaved, refused to exchange my product

I ordered a nike shoe on myntra i got the delivery, after unboxing the shoe i found that the original nike box is missing it is delivered in a myntra box. I reached out to the myntra customer care, i told them about it, however they stated me that it might happen that the box was damaged while packing the product so they delivered the shoe in their on box (Myntra box), they assured me that this is not an issue. I was not satisfied with the answer so i made an exchange request. So the delivery boy along with another guy came to my place on (02.08.19) i handed him the shoe with the myntra box, after checking he refused to exchange my product stating that the original box is missing so they can't exchange. I told him to check the price tag which is there on the box still they denied to exchange the shoe and misbehaved with me. I called to the customer care, i got shocked when they informed me that the delivery boy stated that the product is damaged that's why they declined to exchange the product, however the product is not damaged. I lodge a complain, after few hours i got a mail from myntra stating that they are unable to exchange the product because their delivery boy stated that the product is damaged. I shared the picture of the shoe, price tag and the box with myntra, they checked and told me over the call that this is not a damaged product but still they are unable to exchange as the delivery agent has mentioned that the product is damaged. This is cheating with the customers. Firstly, they delivered the product without the original box then they refused to exchange because the original box is missing. Lastly, the delivery guy misbehaved at the time of altercation.