Changing the word "Provider" in something else

Hi there,

I am translating the front end of the plugin in Dutch by changing some titles in the PHP files. All is going well, except for "Provider". It seems that this is some kind of string i cannot 'just' change.

However, i really need to change the word provider to stylist.
How would i do something like this?

Thanks in advance!

Oh and by the way; compliments on the great tutorials and documentation. Great work!