It is my money and you can't do as you please

We pay our credit card every month according to the amount they put on the system as the minimum payment amount. They then deduct the monthly fees and interest etc. Today they took our savings money because the account was arrears. They didn't phone or ask permission to do the above they just took it. Since when can a bank just do as they please with ones money. That money was suppose to pay for my husbands travelling to write exams. How can they just take ones money without permission? If I don't get that money back before the end of tomorrow I will be moving my business else where. This is unacceptable.