Airtel — bill to high

I travelled to thailand last month and took the travel plan for 15 days costing 1499 inr dates - 9 feb, 2019 to 19 feb, 2019. 0n 18 feb, 2019 i received the message from airtel that my bill got exceeded upto 7900 inr and they are barring the services. I called customer care requesting to unbar the phone but they did not helped and to pay the bill on immediate basis. Inspite to getting the travel plan i have not received any notification that i am exceeding the usage and customer care is not ready to help as they have billed me for 11403 inr now
Can you please help me with it, if i was aware then i would have helped me to manage my usage