Decline rates are an especially nettlesome issue for UnionPay debit card holders, who account for about 60% of UnionPay’s 9 billion cards, as debit cards can only be used in the UnionPay network and in networks that have direct links to UnionPay, such as Payscout LLC, which is the engine behind SecurePlus. Overall, decline rates on UnionPay credit and debit cards can be as high 70%, depending on the type of transaction, the network being used, and whether two-factor authentication is involved. UnionPay is a China-based financial-services corporation headquartered in Shanghai that issues credit and debit cards. Alpharetta, Ga.-based Merchant e-Solutions is also known as MerchantE.