there! I'm trying to do a translation for a client's

Hi there!

I'm trying to do a translation for a client's website. There is language file coming with the plugin, but there are quite a few things missing.
Looks like I can't access certain strings, for example:
Service name:
Date and time:
Lasts (approx):

Another issue: The calendar displays english day names only (Mo, Tu, We etc.) How can I change that?

I work with the german version of WordPress, the day and time formats a set correctly.

I would very much appreciate your help.

Regards,

Kirsten