Pro Sites error after updating Wordpress

After I upgraded Pro Sites and WP to the latest versions my site does not work and debugging throws up:

Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in /home/sheepwal/public_html/themessagewall/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Module/Taxamo/lib/Taxamo/Swagger.php on line 185

Please can you help?
Marc