What should you check first?
- Complete a legitimate banking-app or one-time-code challenge before it expires.
- Check your balance, issuer spending limits and bank policy for crypto payments.
- If authentication succeeded but payment failed, ask the issuer for the decline reason.
When should you stop?
A legitimate challenge should not ask for the full card PIN used at an ATM. Stop if the request looks unusual.
When should you contact support?
Contact your bank through a known official number for issuer declines. Use Gemini's help centre for exchange-side failures, not social-media support accounts.
Use the help centre linked from the exchange's official website. CoinBBank cannot access your account, approve a payment or recover a transfer.
Official sources
This is a documentation-based checklist, not a diagnosis of your account or a record of a firsthand purchase test.