MakeMyTrip — Makemytrip.Com misleading advertisement

Makemytrip gives upto 75% cash back on the booking amount of the subsequent booking if we make a new (first) booking on makemytip.

The discount is as advertised here:
http:/Www.Makemytrip.Com/Promotion/Includes/Hotelstay-t&cs_04042012.Html

I made a new booking (hotel) on makemytrip.Com and used the booking ID of this booking for discount on second booking (hotel).
But when I tried to use the code, I got an error message saying "invalid code".

When I called up makemytrip.Com (around 6 times for this issue), they said that the discount code has already been used. When I asked on which booking it was used, they said they cannot track it.

Then I made the second booking on makemytrip.Com without this "upto 75% cash back" discount.

Then I tried to use the booking ID for this second booking to get "upto 75% cash back" discount on my third booking on makemytrip.Com but again this new booking ID DID not work.

I made all these 3 bookings withing 1 week (27 may, 30 may, 02 june 2012).
This is wrong and misleading and wasted a lot of my time.
Makemytrip should not fool people with such false advertisements.