x_method has to be changed to "ECHECK"
Then you can get rid of:
x_card_num
x_exp_date
x_card_code
Then you have to set:
x_bank_aba_code = Routing number of a bank for eCheck.Net transactions.
x_bank_acct_num = Checking or savings account number.
x_bank_acct_type" = Acceptable values include CHECKING, BUSINESSCHECKING, and SAVINGS.
x_bank_name = Contains the name of the customer's financial institution.
x_bank_acct_name = The cutomer's name as it appears on their bank account.
x_echeck_type = Indicates the type of eCheck.Net payment request. Acceptable values include CCD, PPD, TEL, and WEB.