makesOffer should accept Service

I'm just starting out here, but it seems to me that "makesOffer" should
also accept Thing/Intangible/Service. Specifically, I work for a computer
repair company and I want to be able to say that we provide a service, not
a product. My markup under "schema.org/LocalBusiness" is
` itemprop="makesOffer" itemscope itemtype="http://schema.org/Service/"`.