Syntax Error At Checkout - HELP!

Okay, so during the checkout process on my website, I got the dread "Syntax Error" message once I clicked on "Continue" at the Shipping Option step. So I followed the instructions found at http://forum.opencart.com/viewtopic.php?f=133&t=45863 and NOW instead of getting the simple error, I get a much longer one. However, I have NO CLUE what this is supposed to be telling me.

I am running Opencart 1.5.1.3, fresh install from setup with a custom template (Computerstore from Themeforest). My payment method is PlugNPay, and the checkout process DOES work after you close the Syntax Error window and click on "Continue" again. However, I cannot have customers seeing this error at checkout time.

Below is the error. Can anyone help!? I have no clue what this means and don't know how to fix it!!!

SyntaxError: Unexpected token <
parsererror
<b>Notice</b>: Undefined variable: total in <b>/home3/johncpit/public_html/johnpittman/opencartnew/catalog/model/payment/plugnpay.php</b> on line <b>9</b>{"output":"<p>Please select the preferred payment method to use on this order.<\/p>\r\n<table class=\"form\">\r\n <tr>\r\n <td style=\"width: 1px;\"> <input type=\"radio\" name=\"payment_method\" value=\"plugnpay\" id=\"plugnpay\" checked=\"checked\" \/>\r\n <\/td>\r\n <td><label for=\"plugnpay\">Credit Card (PlugnPay)<\/label><\/td>\r\n <\/tr>\r\n <\/table>\r\n<b>Add Comments About Your Order<\/b>\r\n<textarea name=\"comment\" rows=\"8\" style=\"width: 98%;\"><\/textarea>\r\n<br \/>\r\n<br \/>\r\n<div class=\"buttons\">\r\n <div class=\"right\">I have read and agree to the <a class=\"fancybox\" href=\"http:\/\/www.johnpittman.com\/opencartnew\/index.php?route=information\/information\/info&information_id=5\" alt=\"Terms & Conditions\"><b>Terms & Conditions<\/b><\/a> <input type=\"checkbox\" name=\"agree\" value=\"1\" \/>\r\n <a id=\"button-payment\" class=\"button\"><span>Continue<\/span><\/a><\/div>\r\n<\/div>\r\n<script type=\"text\/javascript\"><!--\r\n$('.fancybox').fancybox({\r\n\twidth: 560,\r\n\theight: 560,\r\n\tautoDimensions: false\r\n});\r\n\/\/--><\/script> "}