BSNL 3G Data
Incorrect Bill Generation

I have opted for the Rs. 4200/- promotional plan in the month of December.

Bill date : 19/04 and Invoice # : 692911522 Due amount : 31545

Since I'm still in promotional period of 4200 (6 months). Why this bill has been generated?

Please let me know for the same. I won't be clearing this due amount.