Airtel — high penalties

Previously penalty was 50 rs penalty on late bill payment with ammount more than 200-250 rs. (Approx 25% of bill limit).

Now penalty increase to 100 rs on late bill payment with ammount more than 200-250 rs. (Approx 50% of bill limit).

I have connection with airtel since last more tha 10 years.

Is any trai norms for penalty over bill ammout with max % per month or every month?