Chinatrust Commercial Bank Co. has signed a deal with Taiwan High Speed Rail to enable the bank's credit cardholders to earn seat upgrades for train rides, the financial institution announced in a statement. Customers with platinum credit cards issued by the bank can earn upgrades from standard to business class seats, the bank says without detailing how much consumers must spend to earn the upgrades. Cardholders can cash in only four upgrades at a time and only when they bring tickets bought at train stations. Consumers cannot cash in upgrades on certain holidays, including the Chinese New Year. The bank issues Visa- and MasterCard-branded cards. The program will last until at least May, with an extension possible if consumer demand is high enough, the bank says. Taiwan High Speed Rail is a high-speed rail network that runs along the west coast of Taiwan.