This bank has a postal debit card. Recently, I noticed that Sanyuan was deducted several times (the interval was less than March). Why is this? My business card also says ...

This is the short message service of the postal service, which costs three yuan per month and will be deducted all the time. If you didn't ask for it on your own initiative, or the postal staff opened it for you in order to complete the task, you should take your ID card and your card to the outlet for cancellation. You can complain to them and find out which outlet it is and who opened it for you.