Calculating SMS Balance in respect of price hike

Please be informed that SMS prices on all routes are likely to be increase by 15 May 2018 as all the service providers together decided to hike the pricing. In this regard, we request you to please consume all the available credits at the earliest. Once the new price is effective the remaining credits will be charged (or) accounted on the new price.
 
Let’s consider the below scenario to check/apply the new pricing with existing SMS credits:
 
Description
SMS Total (A)
Per SMS Price (B)
Amount (A*B)
  Customer Purchased
  1,00,000
  0.09
  INR 9,000
  Customer’s  Today SMS Count
  90,000
  0.09
  INR 8,100
 
Conversion of the above SMS Count:
 
Description
Amount (A)
Per SMS Price (B)
SMS Total (A/B)
  Total Balance Amount
  INR 8,100
  0.09
  90,000
  SMS Conversion
  INR 8,100
  0.12
  67,500