Some of you have access to several different workshops because you have several brands in your department.
The guide here shows how to select and deselect these to your overview:
Click the "wrench" in the left side menu
Check the workshops you want to see in your car overview (you can select and deselect). You can type fx. the city which You wish to see in the search line above the workshops. Then the list will only show workshops from that city. Observe that as soon as You start typing the selection is reduced.
Click on "Select workshops". Now You only see the selected workshops in the overviews.
Please note that you will only be able to see the workshops you have access to: