I see this mistake so often, that I suspect this grammar error may have dropped completely off people's writing radar because we see both versiond all the time. Do you know which of these two sentences is correct?
Coles believes they are the best supermarket.
Coles believes it is the best supermarket.
Should the company name Coles be treated as plural or singular? There are a lot of people who work at Coles, and a lot of stores, so is the plural version correct?
The second sentence is correct. The business name is a singular noun, even if it looks plural, and therefore you must use a singular verb. People often make this mistake, but just remember that a company is a single entity.