Woocommerce checkout error using cardsave extension

Question

I am having a problem when integrating the cardsave payment gateway to the woocommerce plugin for WordPress.

On the checkout page, I review my cart and select place order and the following error appears:

{
    "result": "failure",
    "messages": "

\n\t\t\t
Action failed. Please refresh the page and retry.<\/li>\n\t\t\t
First Name<\/strong> is a required field.<\/li>\n\t\t\t
Last Name<\/strong> is a required field.<\/li>\n\t\t\t
Address<\/strong> is a required field.<\/li>\n\t\t\t
Town\/City<\/strong> is a required field.<\/li>\n\t\t\t
Postcode<\/strong> is a required field.<\/li>\n\t\t\t
Country<\/strong> is a required field.<\/li>\n\t\t\t
Email Address<\/strong> is a required field.<\/li>\n\t\t\t
Phone<\/strong> is a required field.<\/li>\n\t\t\t
First Name<\/strong> is a required field.<\/li>\n\t\t\t
Last Name<\/strong> is a required field.<\/li>\n\t\t\t
Address<\/strong> is a required field.<\/li>\n\t\t\t
Town\/City<\/strong> is a required field.<\/li>\n\t\t\t
Postcode<\/strong> is a required field.<\/li>\n\t\t\t
Country<\/strong> is a required field.<\/li>\n\t\t\t
Invalid shipping method.<\/li>\n\t\t\t
Invalid payment method.<\/li>\n\t<\/ul>",
    "refresh": "false"
}

I tried adding a paypal account which all works fine. The issue only occurs when I select the cardsave payment type.

Any help much appreciated