Vodafone India — Unfair bills

Address:	Surat, Gujarat, 394210
Website:	Vodafone india

I m using vodafone postpaid from last january month of this year.
1st bill of january month was ok.
But last 2 bills of fabruary and march were added mobile internet bill which have never used in month of march and about 100 mb used in fabruary month but it was under the plan of free 2gb data provided me from company itself.
Please guide me what should i do now
I have paid last bill of fabruary month
But this time they have crossed the limits.