If you wish to switchover from Reliance Energy to Tata Power, in fact you should Fill up the application form (Link attached) and handover to the nearest Tata power Centers for all your requirements on changeover. Application forms You may also contact toll free No. 1-800-209-5161 for any information or clarification.
After the switchover the average savings per month at-least 500 bucks!!
Visit http://wotsmybill.com/ to Compare the Cost of Electricity Between Tata Power and Reliance Infrastructure