The bank takes signature of the prospect on the printed credit card application form.One of the terms and conditions may be that bank can hold/ withdraw from any account single/joint, savings/FD etc. Bank are known to issue notice to pay the debt i.e. principle+interest etc within period of ....days, but the notice may be received by the customer on the last day of the notice period,/ or without notice block the payment from the account/ raise debit from the account. If such an action is taken , a legal notice may help, or customer can file in consumer court. It shall be appropriate to cancell your joint accounts.
As a matter of the fair practice bank should provide copy/certified copy of the form/docs to the customer,however usually bank does not.And later the customer has to struggle to get it. However customer as a matter of right can ask for it and bank shall have to supply it.
Salary accounts if opened thru employer are in single/employee name.Since you are not card holder, bank can not withdraw from your account or freeze it.
You may help your wife to take up the matter with bank , get reversal of penalties and clear principle amount.
It the default is due to some dispute , it may be communicated to bank in writing under receipt.
