You can configure a dictionary to be shown only in the Service Completed moment, and populate it with survey questions. In the Service Completed email, provide a link to the user and encourage him/her to click on the link to return to RequestCenter and fill in the survey.
You do need to have Advanced Reporting to report on the survey results, as the survey dictionary needs to made reportable, and then you can define reports against the survey results.
We have provided the base dic