Flipkart — Regarding Flipkart phone exchange policy

Sir,
I have booked a new phone with order id: OD[protected] and OD[protected] along with the exchange of my old phone MI Redmi 5A. Flipkart delivery boy has rejected to take my old phone despite the difference amount I was willing to pay for Screen crack and dents. I made a call to Flipkart customer regarding the issue and they told me that taking of old phone is in the discretion of the delivery boy, whereas there is no such instructions in their sites or application. I would like to know why the Flipkart is showing something in the site and not abiding their own instructions. Please take a look into the matter.