You don't have to use a credit card, but a savings card with signs such as visa or master or American Express can also be used in consumption abroad. The difference is that the credit card itself has a foreign currency limit, which can be directly consumed, and then returned to RMB and then purchased to the corresponding currency. There is no overdraft limit on the savings card. You need to change it into the corresponding foreign currency, such as US dollars or euros, then deposit it in the savings card and go abroad for consumption.

Ordinary UnionPay cards can also be used in consumption abroad, provided that the store where you swipe your card has installed a pos machine with the UnionPay logo in China, which is a big restriction, because foreigners still use their own visa or master.

The tax refund you mentioned has nothing to do with credit cards. You don't need to promise anything. Don't listen to that fool. Savings cards can also accept tax rebates.