Hi,
this seems a bug of your template, all Bootstrap dropdown menus not works in responsive mode. To fix add this CSS code to your custom.css
.jsndatepicker.dropdown-menu{z-index:99000}
in your template is included code for dropdown menu (file is
http://crcmembers.co.za/plugins/system/jvlibs/javascripts/jquery/bootstrap/css/bootstrap.min.css), it assign z-index to 1000. In responsive mode your site have tag BODY with z-index greater than 1000, so bootstrap dropdown menus are behind.