All my dear friends, here is the same problem with me also. My billing date is 15th of every month. I changed to freedom@night on 18th October. Now my bill has been generated on 16th November, which shows me that all my usage has been calculated as per the default plan, whereas, i had migrated to the freedom@night plan on 18th of October. My unbilled usage is also going up every day by Rs. 40-50.
I called the Customer Care, they registered my complaint and told me to solve it within 72 hours.
Lets hope for the best.