Just updated 'subscribe by email' plugin and now getting this? Can someone help ASAP?

Please see Link removed at members request

Getting error
Fatal error: Call to undefined function get_blog_details() in /home/rrokngem/public_html/thehouseofdog.co.uk/wp-content/plugins/subscribe-by-email/inc/upgrades.php on line 71

What can I do please? Could do with fixing this ASAP. Can't get on live chat and can't access admin atall. If someone replies please can they keep an eye on this thread for my response as I don't want to wait 4 days for another answer, it's kind of urgent!