Vodafone India — Bill received for non called special number 51717

Address:	Mumbai City, Maharashtra, 421503
Website:	Vodafone.in

I received my second bill after port to vodafone for the month of may 2017
I was surprised that i have been charged for number 51717 that i have never called. I see that there was two days call are mentioned for this special number and charged me 1500 rs.
When i called customer care they were advising for reducing credit limit, but not providing solution, when i asked to register complaint told me that will receive call in 24 hrs. But no reply from vodafone then i sent mail next day received called but they told me that charge is applicable as you have called but i have never called on this number what ever they have billed to me.