Cell c don't want to add a payment method

There was ***** on my wifes bank account, so she changed banks,all her debit orders changed to her new bank account butt cell c. In store and customer care says her new account must be active for 3 months before she can change her payment details.so don't know how they will take there payment because she closed her bank account,and they( cell c) don't won't to add another.