Indigo Airlines — Discrimination in refund amount

I had booked my tickets from mumbai to nairobi via indigo app in super 6e fare…then i recommended it to my friend and my brother by which they also booked the same route on different dates. But when we all called off our trip and canceled out tickets they got charged zero cancelation charges and they charged me 6000 per pax (Total 24000)…. I contacted their customer care but they kept saying that theor 100% refund is a system glitch but we cannot give you full refund and bluntly denied any help…i request that they should refund 50% of the deducated amount of cancelation to my account…my pnr is e8k86h