Get Prime for 709 trick, maybe works only for mobile buyers

http://www.ama...in
1. Everyone knows Join Prime & get ₹200 cashback offer
2. If you are planning to order a mobile, add it. Use ICICI cards. Your 10% discount gets applied
3. At Place Order window, amazon suggests adding prime. Add prime from here only to cart. Don’t add prime from anywhere else.
4. you will get 10% discount. (Rs.90) . Maybe its 99. didnt notice properly
5. you will be automatically eligible for 200 discount as the 1000 condition for 200 CB gets satisfied

I tried adding other items for 5k, I didnt get the suggestion to add prime. I got only for mobiles