The myki ticketing system used on Melbourne public transport arrived in the middle of a privatisation push (since failed) and now operates as some weird entity that the train station staff have no control over. So when you’re faced with problems they cheerfully respond that there is nothing they can do about it, yet the machines continue to refer errors to them.
So you’re trying to replenish the balance of your transport card and the banknote reader is playing its game of complaining your money isn’t flat enough to play billiards on, when it decides that it won’t return your money anymore. Success? Has it exchanged the money for transport credits? No, your money is so inferior it’s determined you really don’t want it and the bill shall be set aside, oh and it won’t credit any of that to your card.
20 minutes of wading through a call centre and the promise is your money might be credited within 10 working days, in the mean time you need to add more money to your card (woe be you if that was the only money you had on hand, there will be no travel today). The machine knows how much money you inserted and delivers nothing, it would be interesting to see how a cashier would try and justify such blatant theft.