score:2
It's worth nothing that return flights are always from A-B-A. You're asking for an open-jawed (sort-of) flight - and that's almost always two one-way tickets. Sometimes on kayak.com they have variants that'll show up if you select multiple airports in your "return flight" - you could try that (in the "from" box, you can put MAD, and in the "to" box, put "DEL,BOM. However it may just find the cheapest return flight to DEL then. But it could be worth a try.
I'd suggest Flightfox as another possible option. It's like an online travel agent - you pay a small fee, and their experts find the cheapest flight they can for you.
What you could do is create a contest on there, and indicate what you've found, but that you'd like a way to book it for the price you've found, or for less if they can ;)
(disclaimer, I occasionally compete on there as an expert - there's a discount link in my profile)