English translation: transit services sales personnel.
Login or register (free and only takes a few minutes) to participate in this question.
You will also have access to many other tools and opportunities designed for those who have language-related jobs (or are passionate about them). Participation is free and the site has a strict confidentiality policy.
Explanation: More context is needed for real accuracy; the terms are too general to stand alone (and this is obviously why it is difficult to tranlate...). From the information you give I assume that these Kaufleute provide, and market, the maintenance and repair service for buses and streetcars. 'Dealer' is a general term for a buyer and seller (i.e. provider) of a product or service. The English term 'service' has meaning both 'regular maintenance of a vehicle' and 'Leistung' in general, and here should be in the singular.