Plugin with https

I have used your plugin on a closed site using https, but am unable to get the plugin to link to my Easy!Appointment site (also on https). If I accept the security warning it will load the E!A display but with a AJAX Error.

To me it looks like the plugin is only using http and not https to call the E!A site. If I directly connect to my E!A site with https it works great, but if I use http I get the same error.

How do I update / edit the plugin to use https?

Thankyou in advance

Tom