Happy Easy Go - Flight E-ticket confirmation not sent

I made a flight ticket booking through an app called happy easy go on **th April ****. However, I did not receive any e-ticket confirmation message though they said it'll be sent after * hour. When I inquired about it I received a message from them saying I have to pay an extra amount since there was a fare hike. I can assure you that it was a lie because when I checked the fares again there were no changes in the price of the ticket. I called them through the customer care number to clear the doubts but they said they'll call me back soon but I did not receive any calls from them. When I tried calling them back it said that the number does not exist. I tried calling them from my other number but they did not pick up my call.
I can also show you a proof of evidence from other consumer complaints.