Hello DebH
Thank you for your request
In order to alter the means of payment, log into sbb.ch or on the SBB Mobile App. Under «Profile» and then under «Payment method» your details may be modified. First cancel the existing details by selecting the button «Delete». Then enter your credit card/PostFinanceCard details and click on «Save method of payment».
For security reasons, only the account holder or the account user may do this.
Have a nice day
Kind regards
LevinA