I had the same exact issue. I entered all birthdays in the dd/mm/yyyy format but when I clicked out of the box, it subtracted one from the day. I have video showing it doing this. Because of this, all of the travelers on my reservation have a birthday that is one day off. For example, if I enter a birthday of 2 May 1992 as "02/05/1992" and click out of the box, it changes the birthday to "01/05/1992" To correct this, I input all birthdays with one day added so that they showed correctly. I also have video showing the birthdays displaying correctly before purchasing and then the tickets now displaying the birthdays as one day more. This is an issue that needs to be resolved immediately on SBB's website. Please advise what I need to do here. Do I need to request a cancellation of my tickets and rebook? I find it hard to believe this issue cannot be corrected on SBB's end as it is a technical issue that is not resolved on its own website. It is terrible customer service to ask us to pay to call in to a service number to cancel tickets and then rebook when it is SBB's fault.