Fatal Error with NMI interface

Hello, we have been using WordPress as an ecommerce site, with success for the last 12 months. However as of 3 days ago customers starting getting this error when they are trying to use their credit cards when checking out on the site.

Fatal error: Cannot use object of type WP_Error as array in/home/labfocus/public_html/wp-content/plugins/jigonmipay/nmipay.phpon line 215

We are not sure why or how this started and then, of course, the million dollar question how to fix it. We are using WordPress version 3.5.1. We are still new to the wordpress universe, so if there is any information that I am unintentionally omitting that may help solve the issue please let me know.