Airtel — billed for international roaming even though I did not request or sign up for international roaming data usage

Address:

500035

I went to airtel customer care store in gachibowli, hyderabad and requested the service representative to convert my post paid plan to pre paid plan of airtel, because i am travelling to usa, the customer service service representative advised not to convert the plan and suggested to keep the same plan and pay 3 months bill in advance so that the phone will not be disconnected, he said that he is going to active international roaming plan for free, incoming sms will be free. I also told him i do not need any data during roaming, also i was not having any data plan for my phone at any time. He told me that there will be charges for only if my make calls. To my surprise i received a bill of rs 3458 for mobile internet charges which actually i did not use at all. The system was using internet for back ground applications mainly whatsup which i was unaware. When i do not have any data plan why the system picked up back ground app data is the question. I am sure many customers like me will be surprised with the bill.
I request airtel to credit the amount charged for mobile internet. My airtel relationship no is : [protected] and my mobile no is 91-[protected]