Airtel — Auto Activation of services

Address:

Mumbai Suburban, Maharashtra

I recently ported out my number from vodafone to airtel. On 19th March, I was in Delhi in a meeting when suddenly I got repeated messages from AT-AIRNF saying "Thankyou for using HELLO TUNES SUBSCRIPTION sevices. you have been charged Rs. 30". Since I had not started any of these services and neither wanted to, I reported the incident to 121 from Delhi (under roaming) but the just kept my call on hold each time. I also wrote an email to he corporate customer care regarding the issue on the same day.
After a couple of days, I received an email from corporate customer care that the Hello tunes shall be deactivated. However, when I inquired about payment of the charges, there was no reply from the customer care.
The issue still persists.
Why should I pay any charges when I have not subscribed to any services. Is airtel trying to make money by doing such fraudulent auto activation activities.
Who is responsible??