Bro u can try following steps for package change:
1. Download and login to airtel thanks app.
2. Change your current pack to any low cost monthly pack.
3. The remaining unutilised pack amount balance will be automatically credited in your account instantly.
4. Then check if the refunded amount is greater than or equal to Rs.1407. (In case it is less than 1407, then simply recharge the difference amount).
5. When balance becomes Rs.1407 or more, then call customer care to activate the package from the main balance.