I’m sharing the steps which i followed to purchase paid app in playstore using idea direct billing payment option.
First, goto www.payments.goog...om in your desktop by login your gmail account.
Go to settings (Right top corner)
Change/Update your address to India Address
Now open your Google Playstore app in your mobile (Use any network mobile data, don’t use wifi)
Go to accounts>>Payment Methods>>Add payment method by click + symbol.
You will found ‘Bill My Idea Account’ option (if you not found this option, wait for some time) just tap on it. It will verify your Idea account by sending one sms, so before proceeding just confirm your idea sim is set for default sms otherwise change your idea sim to sim1.
After successful verification, goto the app or content which you want to download and do a purchase through Bill my idea account payment option.
Amount will be detected from Your idea main account balance, so just confirm you should have enough balance to purchase the item.
Extra service charge of Rs 1.60 is also detected from idea end.