AU does have Amazon and Flipkart option usually, may have run out of stock. They don't show up at first, will have to search for it... Very often, its the rs 5000 voucher that is available and stocked up.
However, vouchers do not give you best value for rewards. Use it for travel booking. The convenience charges are also lower than other common portals. Travel booking gives you 0.25 value for point. When I used it recently, I even got a better rate than EMT/Yatra/MMT for my flight.
I haven't tested it, but I think recharges also give you Rs. 0.25 value...