On agentOS, there is no need for the Contra button as for every action there is a reversal which can help.
Some examples of this would be:
To reverse a charge, you would apply a refund.
To reverse a refund, you would apply a charge.
To reverse rent that has been paid to a landlord in error, you would apply a "manual rent refund" which will send the money back to the tenant.
To undo a payment group you have made through making or taking a payment and not yet reconciled to a statement entry, you may simply delete the payment group from "All Payment Groups" and make or take the payment again
For any instances whereby you feel you require a Contra option, please contact agentOS support and one of our advisers shall be on hand to help.