Mail and telephone order

Yes I have finished the first ¥100 and then topped up another ¥500 with BigPay, no OTP. Also finished the ¥500. Didn't encounter any problem using it to make payment here in China.

Used it for metro, food, attraction entrance fee, shopping....basically all scan and pay can be used. So for Didi, you can choose cash as payment method, and make payment by scanning the QR code to pay upon reaching your destination.

For this TourPass virtual prepaid card, it seems like once you have put in the card when you first apply, you can't change it. But who knows, probably later update may be able to do so. For example, they have added the feature for us to add TourPass to home screen which wasn't there on the first day it launched.