Airtel — international roaming data fraud

Address: New Delhi, Delhi, 110015

Im highly upset and want to file a complaint in consumer forum against airtel.
Even after getting activated on international roaming for thailand, which i usually do in all my international business trips but this incidence is pathetic, i hv been send a bill of 25k for consuming 6gb extra data usage. Which must be a technical glitch.
I wrote so many emails stating if i had intentions of advance data usage why would i buy a data pack. Its completly unintentional.
There are no messages no email for a given data consumption bytes. Nor they inform the client for further activating additional data.
But they are so rigid that they dont even value their loyal customer.

Its highly unappreciated from a major brand value. If there is anyone who has also gone through this pain. Pls contact. I hv to turn legal for this.