I think that "who" is acceptable. Otherwise, I prefer "that" to "which", unless you intend it to be nonrestrictive. And keep in mind that "adverts" is a British term, so if you're writing for an international audience, "advertisement" is probably better.
I would advise you not to use who with things. You would be in a minority, in both British and American English. Take a look at the corpuses (BNC and COHA).
If you wrote, for example, "a company who makes a large profit", I would say that was substandard English (or, at best, very informal). A company may be a person (in a legal sense), but this does not justify the use of who in this sentence. (In legal texts you often see he referring to companies, but that is just a convention.)
When referring to persons, the rule is different in that you can use who or that. For example, "A person who/that eats too much will become obese".
In technical terms, a company is a "legal entity": all entities may be addressed as "who" although this practice is rarer where a non-human entity is the object rather than the subject.
The matter is complicated by the way "company" is viewed. The company would have us believe that it is full of individuals who are there to help us, hence "who"; others might see "company" as a faceless monolith, hence which/that.
As ever, whenever there's a low frequency, look at the underlying sources of an ngram:
A Picture of a Company: Who We Are, what We Do, what We Want
Lord Reid said that a company may be held criminally liable for the acts only of ... the board of directors, the managing director and perhaps other superior officers of a company [who] carry out the functions of management and speak and act as ...
The chairman and the directors of a company who do not prepare the attendance list of those present at a meeting in compliance with the provisions of Article 99 shall be liable to a cash penalty ranging from twenty thousand Rials up to two ...
For the purpose of any enactment in this Law which provides that an officer ofa company who is in default shall be liable to a fine or penalty, the expression " officer who is in default" means any officer of the company who knowingly and ...
A director of a company who acquires or disposes of a relevant interest in shares issued by the company shall,
Any director, employee, or shareholder of a company who - (a) fraudulently takes or applies property of the company for his own use or benefit,
And so on. However, there is one from 1872 which could do as an example of a company being referred to as "who":
... and that the policy-holders who should decline to accept substituted policies should be entitled to keep their old policies on foot by paying the premiums to the A Company, who undertook the liabilities of the M. Company in respect thereof.
I feel that the graphs again only confirms the use. Post #8 is a particularly good example where a company personifies itself by the use of "who" - potential customers relate to "who" and think of "people", whereas that and which are faceless monoliths.
As Andy notes that there are, within all the search terms used so far, instances of such uses as "the management of the company who are all men" and "The product of the company that/which was withdrawn from sale" etc. will be skewing figures. Google Ngram steadfastly refuses to consider captialisation: "The company who/that/which"
The difficulty here is that while the ngram is case sensitive, the linked Google Books search is not. It's also not an exact phrase search, even though the search phrase is within double quotes. That means that the books you find from the links at the bottom may include books not used in the ngram. That's a particular problem if you try to find sources for an AE/BE comparison.