Vodafone India — false bills

I was using a vodafone postpaid number from a long time.in april 2017 i shifted to europe and then this number was rarely in use after may 2017 this number stopped working.. I contacted vodafone india about the issue. They asked me to pay unnecessary bills of 5000 to restart the connection by applying some unnecessary roaming charges. After one month this number stopped working again. When i enquired about it. They told me that it has a pending bill of 15000 even after the number was not in use. Now they are driving me to pay the bill amount otherwise they will take legal actions