Blocking a seller

Hello Carl. Easy answer here. No.

However you can sometimes use a workaround. For example you can restrict the search to casual sellers, or local sellers if it's an International seller clogging things up. 

Kia ora Carl, it's not possible to block sellers from showing in your search results. You can try refining your search criteria to reduce or exclude the types of listings they are offering and then save the search so that you are getting results that are more relevant to you.