I am able to add a sort code, account number and name to the batch payments field as can be seen below. But I am not able to update the "Bank account name" or "Details" fields using the API.
Currently I use contact.BankAccountDetails = "678989 12345678 aj"
which works as seen.
I have tried setting contact.BatchPayments
which has no effect.
The Xero docs are not helpful on this point.