Called NS customer services today to find out where money on the travelling card of kid had inexplicably gone.
Turned out the money was accounted for, but they had indeed made a mistake. And no, that that mistake made that we got problems was not their problem. On top of that, kid should be grateful that she did not get fined in the train.
WTF, she paid her travelling costs, they made a mistake, and kid should be grateful she did not get fined for not travelling properly because of their mistake?
Customer services did withdraw those words, but I do not do well on imposing behaviour like that.