Caller ID free? what free??(bombay). Review on Airtel Mobile Operator

I took airtel postpaid from a special offer at IIT bombay mood indigo festival, where they offered me zero rental for 6 months & caller id free for life. about after 5 months they started charging me Rs. 50 as caller id charges, when I contacted them several ties they said it was ''free as a promotional offer'' . I also contacted the person from airtel who gave me this connection at IIT, he personally confirmed from concerned authorities that I should not be charged & I will be given a refund. but still I was charged again next month too. then I tried calling this person, he didnt accept my call. I also emailed airtel customer care , they said they will reply within 24 hours but it was more than 1 week I didnt get any email reply .

Also before going for regional roaming, I had asked on customercare 121 that calling/smsing on 121 for enquiries was free on roaming too, but in my bill I was charged Rs.3.45 per sms I sent to 121. then I complained them & asked for a refund, they didnt give me any refund, & said ''inconvenience caused is regretted''.