Travel Triangle — Booking cancelled - high cancellation charge

I have booked a trip with travel triangle for 9 adults and two children and they have quoted the price as rs. 194620. I have paid rs. 40220 as advance. However due to unavoidable situation I have cancelled the trip and requested for a refund. Travel triangle levied heavy refund charges of rs. 39180. They mentioned that this includes taxes. I told them am willing to pay cancellation charge of 9*2000= 18000+ tax on this 18000( if tax amount isn't included in rs. 2000 per person cancellation charge) which is very reasonable. But they refused to refund the balance amount. Cancellation fee can be charged but the customer shouldn't be overburdened. Moreover I wasn't even issued a proper invoice with gstin. I need help to get my refund back as I have already cancelled my flight tickets with cancellation charge(@ rs. 500 per ticket). Pls help