Trai — Complaint Against VI for Wrong billing

Hi My Number is [protected], i am using Services of Vi. My Posta paid bill is of 471 per month including of Taxes.
My billing cycle is 10th of every month & i have paid all my bills till 10 Nov'21 which i have paid on 29th Nov'21 as per my due date.
I have received my next bill of 471 on 11 Dec'21 as per schedule which i am supposed to pay by 26th Dec'21. Meanwhile i have again received a bill of 471 on 20 Dec'21 for period of 11th Dec'21 - 20th Dec'21.

Now i am calling to their customer care and they are giving excuses like:
1. Your one cycle was missed by us so we are clearing that
2.Your billing cycle is changed due to that you have to pay this bill.
3. We are now generating bills for 45 days as you are corporate client.
4. You have missed your bill in 2016 & now we are charging that amount.

I have checked all my bill of last 6 months, none of the cycle is missed & all bills are paid so there is no chance of mismatch.

Kindly help against this.