If you don't know what the repository and service patterns are, check out this article:
While I had made use of the repository pattern before, I still made the mistake of putting the method getOfficeContactData() into a service class, even though the name (the data part) should have made it obvious that this is something that belongs into a repository class. In addition, it was shared by two service classes!
Thanks to my code reviewer who pointed it out to me. I think I now understand the purpose of each layer better and will pay more attention to where I put methods in the future.