When a payment fails, first find out which part of the transaction stopped. A merchant that cannot take your chosen payment method, a wallet that cannot use a linked card, and a card issuer declining authorisation call for different questions. A screen message alone may not identify the cause.
At the counter: establish what the merchant accepts
Ask whether the merchant can accept the method you are trying to use and whether it has received any payment confirmation. Keep the order number and the exact error message. If the merchant cannot accept that method, ask what other method it accepts before trying again. A failed attempt does not prove that the card itself is blocked.
If a mobile wallet cannot bind or use your card
China's State Council working-and-living guide says an overseas-issued card must be verified by its issuer to be bound to a payment product. For a binding failure, the guide names the payment product's customer service and the issuing bank as the relevant support routes. Record whether the failure happened while adding the card or during a later purchase; those are different events. Check the wallet's own notice or service agreement for the card brand, limit or charge applicable to that product. The national guide does not establish a single limit or cause for every failed transaction.
If the card issuer reports a decline
Use the support route shown by your card issuer to ask whether it sees the attempted transaction and what action, if any, it requires. Share the time, amount and merchant name through that secure channel. If the issuer has no record, give the wallet or merchant the error details so it can check its side. Do not repeat a payment blindly if it is unclear whether an earlier attempt was charged; check the transaction records first.
Keep the immediate purchase separate from the diagnosis
The State Council's payment-services guide describes mobile payment, bank cards and cash as different payment options in China. A backup method can help complete an urgent purchase while the original failure is investigated, provided the merchant accepts it. Acceptance of an overseas card, the availability of a wallet payment and an individual issuer's decision are separate matters; none is guaranteed by the existence of a national payment guide.