First of all, remove all Gmail account from your device, just remain 1 acc
Then add upi in Payment methods in that acc ( go to play store and add from there, in payment methods area )
Then open BGMI, log in your acc, and buy 650uc legitly by your payment method ( upi )
Done, Uc loaded successfully
2nd part ( now refund the money )
Clear data of chrome, and then open chrome and type play.google.com
Then click on 3 lines in the left top
Then click on account and then order history and then your last order 660 UC
Click on report problem, then click on I have purchased this by accident, then type in the description “I have purchased this by accident, please refund my money” and then click on ok
And then your money will be refunded within 24 hours, after getting money, add another Gmail, do the same thing with the new Gmail.
NOT TESTED BY ME.