I've turned off the redirect plugin.
In the PXPAY plugin we do not have any values for the Cancel URL or Return URL.
This has not been changed since you have installed the PXPAY plugin.
I tried using PXPAY to purchase and got a successful transaction, but on hitting the NEXT button I then got a 404 error.
This was the address bar text. Is anything missing or truncated?
http://arthrem.co.nz/pxpay_4.php?result=v5Qhsh-r7s4Q124hqKG_PASU3IEsailgHodWoLXIG3ofPfj7EkfksccZbqmCu6B6AUQwBwN5GzCMun1Aob8AgFKD50v7vHoq4iI4RB1-JAZD0L7IQuW_B_PQJfNNUpqA-ngVs0vKRuBoM83hRYV_ZdNeujwzFW1D8jY1cIcYQHRftiUA1IOTP6KhB8wCzlZXQFjaxoiUGl1DJx5ll-LavKX5DfJcwaykcwh76OhTwmJUKUaJh6iEApobbOaCYTz_hEvXn1BIUwdktOOIlZtKXcNIhu6LPOrlJb5N1FjC3YExCZYpnlJ-uYnqoNfi9Xz8zly0Xyd3w1YrC7ttBUOIxKrLjS9-q5Que2-R0r0DH8lG0Ue6tivFEY3sKP6uvDMKUCQMsDd-Ol1m9jbMMEBvJ_GCnVzQayHHdhtHi8lzBZtU_65GfXwIzyxofvL6qzM1CccIOF8dsVkaFGEy9Q2eYnEEcDoIzFr4KBwjkk79WNKIr88ANwHUnbdwW65QXdPXWQLSfZtbaWsH7wyYlgfvVKosVQe57trtdY7yJ8g86xApU=&userid=BenefitHealth
I don't know what else to check.