Flipkart - Order Cancelled Without Notification

We paid advance payment of Rs ***** on placing the order for HP envy ** i*(*th Gen) on **-**-** on Flipkart. The order was shipped from Hyderabad on **-**-** and was out for delivery on **-**-** but it was cancelled without notification. On calling customer care they said seller cancelled due to item being out of stock. If the product was indeed in shortage, how come it was shipped and we got updates? Were the alerts fake?
After placing order, *-* items of the same were still available for sale on their page.
On inquiry, it was informed that money will be refunded in * working days ie by **-**-**. This is loss of interest of ** to ** days @*% per day with mental agony.
We were tracking this laptop each day and got no forewarning about this fraud. This is how Flipkart is fooling on Megabillion Day Sale.