Airtel — amount rounded to the nearest number. additional amount not adjusted in the next billing cycle

I am a subscriber of airtel. I use the online payment mode. Every time the bill amount is rounded to the nearest higher value. If the amount is rs 478.89 it gets rounded to rs 479. Even if the amount is rs 478.05, it gets rounded to rs 479 and not rs 478. The additional amount does not get reflected in the next billing cycle. I had requested to change the plan to 399 plan. It took six months to get the new plan. Though they claimed it as their technical fault, they charged based on the previous plan which was very high. Every month i need to call the customer service and get the adjustment done.

Airtel has to make a provision to get the exact amount and not a rounded amount.