Happy Easy Go - Refund not proccessed

I've booked my Indigo flights ticket via happyeasygo.com on **/Nov/**. Due to COVID-**, my flights got cancelled on in March **. Partial amount for the fligth cancellation was converted to credit shell and partial amount was refunded on **th March. I tried calling happyeasygo on **th May regargding the refund, they asked me to cancel the ticket through their portal so as to get the refund. I tried cancelling the ticket through their website and then I got a mail telling me they are not accepting my cancellation. I've called them again and they told me my ticket cannot be refunded and I have to utilise my credit shell first and then only I can apply for a refund. So they denied the refund. But Indigo has already refunded the amount to theri bank accounts, how can they hold my money into their account? If the refund is already issued, who are they to hold that amount? Is it a new kind of scam going on? Are they trying to hold everyone's amount so as to earn profit through bank interest?