There can be several reasons for a payment to be declined or blocked. Most often, this is related to exceeding deposit or withdrawal limits set by the bank or the National Bank. The bank’s security system may also flag the transaction as suspicious if it appears unusual for your profile (for example, a very large amount, frequent consecutive transfers, or a payment to a cryptocurrency-related service). Some banks restrict transactions with crypto exchangers in accordance with internal policies or regulatory requirements. In case of a block, you need to contact the bank’s support service, confirm the purpose of the payment, and, if required, provide documentation.