Reliance Communications – Sent Pre-litigation email for dues 1year later after terminating connection.

I was using a reliance CDMA Postpaid RIM number, but due to my service, I had to take a transfer to Pune, Maharashtra state.
I had decided to pay the existing months amount and terminate the service, I went to nearest Reliance store in Kothrud and paid the outstanding amount and asked to terminate my connection. I was acknowledged the same and hence, I gave up that number, that was around Mid September 2012.

1 year later, today 23rd Dec, 2013 I got a Pr-Litigation notice email, for an amount due Rs. 750.
This is total fraud, They had my email id, if this existed, why didn’t they get back to me in October or November 2012, for non-payment of bill?

This is not acceptable at all.
What should be done now?