Why don’t you extend your budget upto 14K?
Sony Xperia U (with dual core & excellent benchmark scores) is available at 13.5 K (with dealer warranty).
Sony Xperia Neo L & Sony Exricsson Ray are also available with few online dealers for 13.5 range.
I am not familiar how these dealer warranty works, but some are offering warranty through a third party network called ServePro.
If your budget is already upto 13K, then please extend it few more & go for Xperia U. With the dual core processor & ICS, you will not regret for the next 2 or 3 years. With manufacturer warranty, it might be close to 15K, please check with your local stores.