Travel Agency Not Providing Refund But Voucher

Booked a Holiday Package through MMT, due to recent terror attack had to cancel the trip, now after 30 days MMT is refunding the amount in voucher which can only be used for booking another trip, can I register a complain regarding this as I dont want a voucher but a refund of money. They are saying as per their terms & conditions when we book a holiday of package they can only offer a voucher upon cancellation.