Makemytrip - Cancellation fees charged despite buying cancellation assurance

I booked air tickets using makemytrip.com for two sectors - **th Apr ** from Chennai to Delhi and **th Apr from Delhi to Chennai. I bought cancellation assurance by paying additional amount of Rs ****.

Now when i tried to cancel my one way trip from Chennai to Delhi I was charged full ticket amount for cancellation and I was told cancellation assurance is not available as I am not cancelling complete itinerary.
They charged full amount for cancellation assurance but providing benefit not fully. When asked about it why it is not mentioned at the place of cancellation assurance comment, I was told it is available in terms & conditions after three clicks.
Pure case of intentional cheating to hide information in fine print.