This is my experience with Airtel Prepaid card. My father uses it and has very less usage. One day he gets a call from a number 99870... and the moment he picks up, an automated voice starts playing back promoting some advertisement. After some mins again another call comes from a similar number but strangely displayed (+9987072735, no ISD code or india code of +91).
It went unanswered as my dad wasnt around. He came back and saw and asked me to call back the number to check who it was (assuming it must be some relative from overseas). I dialled back the same number and got a message that it was an invalid number. I disconnected the call and to my shock found that 9.32paise had been deducted from the balance for this "invalid" 3 seconds call.
I called up the call centre and expressed my grievance and was told that there was international call and as you had called back the deduction has happened. I insisted that if its an international call why is there no ISD code and why am I being charged for a call that says invalid number. Then I stressed that I had got a call from a somewhat similar number promoting advertisement. THe call centre executive was unwilling to accept, I told him fine let me call the same number from a different phone and make him listen to it and also I threatened of complaining to TRAI of using unfair practices.
Immediately the executive promised that he will reverse the money to card. After 10 mins I got my money back. Hope the semiliterate population of india which uses prepaid card abundantly is made aware of this unfair practice being used by these corporate honchos. THanks and Regards, Balvinder Singh