Akbar Travels Online - Unreasonable additional charges

I made an online flight ticket booking from www.akbartravelsonline.com to fly in DOHA-COCHIN-DOHA sector for my family. The fare shown on the website was Rs. **,***/- and I paid it online. After a few minutes, I received an email stating that my one-way ticket is issued and need to pay an additional Rs. **** to issue my return ticket. I immediately called their customer service and said I dont want to issue a one-way ticket if they cannot issue both-way for the mentioned amount. But they were so arrogant stating that they will not refund my money. On duress, to avoid further losses I have to pay the additional amount. Now, can you please advice to which authority I have to approach to teach a lesson to this travel agency? It is not only about the money but also about their such behaviour.