Airtel - charged wrong bill on international roaming

i have been charged ***** rupees extra on my two months bill on airtel international roaming, even when i have activated my plan of **** for * month on **th september, and recieved a conformation message that your * month is activated,they have charged me for every day pack, i am following them for the last * months, they keep escalating the problem but wsolving the issue, my mind is not totally devastated, they have once disconnected my network due non payment of my bill as it was wrongly charged i have not paid it, due to that disconnection i had huge loss in my business i was not able to recieve or do call , currently i am in usa , i am stuck with this issue, calling them every day wasting hours n hours everyday calling customer care and not getting the issue resolved