Flipkart - Cancelled showing Customer cancelled the product

I ordered Vivo Y** on **nd January with offers. I got exchange offers with my old Yuphoria device and also got **% off on SBI credit card. Now after ordering the product was coming as usual. On **th it showed out for delivery. I was not available that day, that's why I directly call to flipkart on **:**AM(Because previously same kind of thing happened with me in my other account, and they showed me courier boy cancelled & I was told I should contact flipkart directly), that I want the product on next day. They assured me in one attempt product will not cancel. The courier boy called me on *:**PM, I told him the same, want the product tomorrow.
Now in the morning I saw the product is showing cancelled and reason is return requested. I immediately call flipkart at *:**AM, asked what happened. And I asked them "How the product got cancelled and, I need an replacement product." He told me "I cancelled by myself". I asked how? He stopped speaking, after sometime call got disconnected. I received a message, I will be called on *:**AM.
Next call came from them at *:**AM. Then I asked the reason behind cancellation, They again told me I cancelled. I asked them How I cancelled, By app/site? They were telling "I called Flipkart in the morning and asked to cancel the product." HOW????
I called after cancellation, and they were saying because of that call my product got cancelled.
Then I told them the timings. Then they told me I asked yesterday to cancel. I make them understand that it is also a lie. Cause if someone asks the executive to cancel anything, It will get cancelled immediately. And I called at **:**AM, How the product gets cancelled after a long night? Did they got a dream? Then they were saying "Sorry it may be mistakenly cancelled and nothing could be done."
Q*: How can a site show that the customer cancelled the product, which they cancelled?
Q*: Why they promise those offers they can't fulfill.
Q*: What is the helpline for? To know the same thing the customer already knows?