[Resolved]  Airtel — can't recharge 448 plan using my main account balance

Address:

380061

Hi, my airtel app shows me new offer of 448 plan. But i am unable to activate that plan with my main balance.
I have balance of rs456. I called customer service for help but they told me some recharge can be done by using main balance.
But why some recharge can't done. May be that recharge amount company used for black money.
Why should i spend money when i have balance in my mobile.