Westpac reportedly spent $70 million upgrading its branch computer system last year. Westpac spokeswoman Jane Counsel said the incident had little or no impact on customers. "Westpac experienced a minor software problem which impacted our branch teller network for a short period of approximately 1½ hours on Monday," Ms Counsel said. "The problem was quickly identified and rectified and customers experienced only minor delays to services as all branches were able to implement manual workarounds." But retail customers were told no manual overrides were possible except for the nominal withdrawals. A source close to banking teller networks said the problem was typical of a central mainframe hardware failure. "It's rare, but it happens," he said. "You can bet it's a hardware appliance. When fixed, it takes ages to get all the connections to the branches to fire up again." He ruled out telecommunication outages because tellers still had access to the internet on their terminals.