Airtel — Callertune false charges

I have requested a Airtel fine connection and paid three months in advance for RS. 799 +GST plan. After one month o[censored]sing fiber, they send a bill of 70 rupees . I asked customer care and told them that I have already paid you in Advance .Could you tell me why my bill of RS. 70 was generated. They told me ..I have requested a caller tune on my Airtel landline number and they couldn't even check their system if the service is currently active. I have told them the scenario that J have not requested for it and it should be waived you. You can send me any call recording I had with your company for caller tune, any request raised on my behalf for caller tune, any email I sent you or any email you sent me confirming that you activated a service . They don't have answer to these queries . They are falsely charging customers whatever . This is very wrong. I want to raise a complaint that after continuously following up on call, email and all this mental abuse, my issue is still not fixed.