Vodafone India — Bill charged on fake number 51717 of rs 1680 on my name

Address:

Ghaziabad, Uttar Pradesh, 201002

Vodafone has produced a fake bill of rs 1680 on my name as they say that i have called some number 51717 which is completely false and fake. As this number doesn't exist in the real world. When i address the issue in front of them they said that what their system does is correct and they do not hold any other information. I asked few questions but they don't have any reply they just keep on saying that their is always correct. Few questions to vadofone:-
1. Why 51717 doesn't existed in present or past?
2. How can i make a call on a number which doesn't exist?
3. How can i call at 1:30 am approx when i do not call after 11:30 or so for the past many years?