Flipkart — Order cancelled without my knowledge after 15 days of not fulfilling my order

I placed an order on 12th June 22. The order was not delivered but cancelled(on 27th June 22) without my knowledge after 15 days. I was continuously complaining for this since 20th June and Flipkart assured me that they would resolve this issue within 24-48 hr. I talk to Flipkart's senior executive too but the same reply. On the 26th I received a call from Nancy from the Flipkart escalation team she said if for any reason the order will cancel they will help to place a new order from any other brand at the same price but today I received a msg that the order has been cancelled by the seller.
I tried to reach out to Flipkart for the same to know why my order is cancelled after 15 days of not being able to fulfil they again said it is cancelled by the seller. Do I deal with the seller or Flipkart? I had placed the order on Flipkart, not on the seller's site.
When I asked why the seller has cancelled this order they said the product is out of stock. Till 26th this product was available on Flipkart, To make the fake resolution Flipkart put that product on "Out of Stoke". If the product was out of stock from the date of order then why it was showing "In Stock" on the Flipkart site If the product went "out of Stock" on or after the 26th then why Flipkart did not fulfil this order with in given delivery time period?
Flipkart is making fool of their customer. Flipkart does not have a valid reason for cancellation.
This is the second within 2 months that Flipkart has done the same for the same product by the same seller.
I want the action against Flipkart so that no customer will face the same issue on the e-commerce platform.