Vodafone — Not changing my service from postpaid to prepaid

Address:	Faridabad, Haryana, 121009
Website:	www.vodafone.in/feedback

I want to change my service from Vodafone Postpaid to Prepaid. I am trying from many days at the service centre of Vodafone at Okhla phase 1. But customer care executives are refusing to change my service and wasting my time. I have been visiting there from last 2-3 days but they are taking no action. I am fed up from this. I want effective action aganst my complaint. My details are as below:

Sachin Singh ([protected])
Address: C-36, Shiv Durga Vihar, Lakkarpur, Faridabad