Happy Easy Go - Company is denying to give me the credit shell balance for flight booking

I booked one flight ticket from Happy Easy GO(CCU-BLR, Indigo), my journey date was *st April. Due to this Covid ** situation, the flight was cancelled and Indigo sent me an email that **** will be in the credit shell. Today I am trying to book a ticket using the credit shell and indigo is asking to book from the Happy easy go and the credit shell will be adjusted.. Fine.. I checked with happy easy go, I can see the flight price on **th Jun is max ****. So ideally I have to pay max ****-**** INR after adjusting the credit shell balance. Happy easy go sent an email that I have to pay total **** INR which is simply unacceptable and fraud. Basically Happy easy go is denying to give the credit shell balance back. In the happy easy go website I can see the flight price is max **** -**** but they are charging additional **** even after adjusting **** Credit shell balance. So that means the total flight price they are asking to almost **** which simply illegal and fraud. I need to you help me in this issue and fix if possible. In this urgent situation they are just cheating the customers. here is my happy easy go booking id-******************. **********- is my number, in case you need you to contact me