Happy Easy Go - Didn t get refund for a cancellable ticket

On June **th I had booked a Vistara flight from Bangalore to Srinagar for **rd July. It was a cancellable ticket. On July *th I noticed that Happy Easy Go had booked a flight that I didn't select while booking (due to some technical issue in their end) and I was the bearer of the loss for their issues. I had to cancel my ticket which was a cancellable ticket. On **st July I got the partial refund of Rs.**** but the remaining amount is just gone. I had been calling Happy Easy Go since then but every time I call they say that they have raised issue for incorrect refund and they just end the call while I am talking. I have recorded all the conversations that I have had with them. This is mentally very much disturbing. If they won't refund the money then why we book a cancellable ticket? It was their mistake in the first place to book a flight which I didn't select initially but over and above that they are doing this to me. I demand the full amount that I paid from this fraud company.