correct region or correct industry?

I have submitted a site about advertising across London and Surrey, the company is based in Wimbledon, Merton.

There isn't an advertising category in the Wimbledon>Business and Economy section

Which category should I have submitted to? London>Bus>Advertising or London>Merton>Wim>Bus

Here's the drill for Regional categorization:

FIRST drill DOWN to the MOST specific REGION category which contains the organization's place (or places) of business.

From there, drill FURTHER down to the most specific TOPIC subcategory which would include the type of organization.

Most (not quite all) organizations exist in a particular place, and so this would (nearly) always find an appropriate category.

There may be OTHER appropriate categories, for those organizations that have regional import (Universities, symphony orchestras, global manufacturers are obvious examples: real estate agents, elementary schools, and restaurants are obvious non-examples). That taxonomy gets more complex, and the editors are better equipped to handle exact placement (or, at least, can consult to choose the best placement).