It is possible to change the bank account number of a current direct debit.
A yogi can update the data by going to Edit profile being logged in and re-entering and saving the bank details.
If you prefer to update the data yourself, you can do this by going to the yogi being logged is as administrator. Click Edit profile. Here you can delete the old data and enter the new bank information. Then you press Save and the following direct debits will take place from the new account number.