Hi milksteak

What you experienced is normal, but of course scary nonetheless. In China, usually the authorization is for the DCCed amount, and you can only know after it is posted.

Technically, all transactions in China can be DCC free. But some of them actually requires some actions before the transactions are logged into the payment systems (meaning the fake options on the slips are pure lies), while others are designed to be operable but neglected by the cashiers (as they have to give some inputs to the payment systems to choose the non-DCC currency, and the systems always choose the DCC one if no inputs are made to maximize profit).

In Shanghai, people follow the rules much better than people in Beijing. I've encountered much fewer forced-DCC instances there. Some places in Shanghai even don't have the DCC option at all, using POS directly linked to the UnionPay system without any evil tampering from the greedy banks.

In Beijing, if you see the "choices" on your slip, you are doomed already.