Vodafone India — Vodafone number [protected]

I had submitted a disconnection request on 01 April 2016. Despite this I received a bill of Rs. 3, 882/- for January and February 2016 on 18 Mar 2016.
After which I paid the amount to Vodafone and again submitted a request for disconnection.
Despite all this they have again sent a bill of Rs. 1974 on 19 April 2016.
The bill claims that there has been usage of data while I have not used the dongle in this month at all.
This amounts to sheer harrassment and cheating that despite repeated requests to cancel the connection action has not been taken.