punctuation - Proper Apostrophe Usage with Initialisms: CCS' or CCS's?

I work with a company whose name is frequently reduced to an initialism (acronym). Let's say the name is "Cool Computer Systems" (CCS). I am engaged in an ongoing, bloody battle with the marketing department, wherein they insist the following apostrophe use is correct:

Buy CCS' New Product.

Reading that line brings visions of crying 4th grade teachers and librarians to mind. I am quite certain that it should be written:

Buy CCS's New Product.

---

UPDATE:

The examples are in title case because the sentence is the subject line of an e-mail.

---

UPDATE:

Their argument is that "Systems" is plural. I say that plurality doesn't matter, because "Systems" is part of the name. The name as a whole should be handled as a singular entity, because the company is, in fact, a single, legal entity. Thus, the possessive form should be written:

The Emperor's clothes

Cool Computer Systems's clothes

CSS's clothes

Answer

According to the Guardian style guide:

The possessive in words and names ending in S normally takes an apostrophe followed by a second S (Jones's, James's), but be guided by pronunciation and use the plural apostrophe where it helps: Mephistopheles', Waters', Hedges' rather than Mephistopheles's, Waters's, Hedges's.

So I would likewise go by pronunciation write it as:

Buy CCS's New Product.

Or rewrite to avoid it the apostrophe altogether.