Because your card is an ordinary savings card, there will be no overdraft credit limit in the card account, so no matter whether you press "savings card" or "credit card", the money you withdraw can only be deducted from your savings account. If the balance in the savings account is lower than the amount you entered, you can only get the prompt of "insufficient balance", and then the transaction fails. Judging from your description, you should get 100 yuan, which means that your account balance is more than 100 yuan.

So, never mind!

Furthermore, if you are still worried and really want to get an accurate answer, please take out your card, call according to the bank customer service phone number on the back of the card (if the numbers starting with 9 * * * and 400 are closed, if the numbers starting with 800 are closed), switch to manual work and clearly state your doubts, and you will get a reply from the bank, which should be able to set your mind at ease.