In my pre-Kindle days, I published a quartet of books through self-publishing, print-on-demand companies, and with good results. Their design teams were excellent, and (thanks largely to my favorite cover-art photog, Paul Grenside), I came out of it with some sublime products.
But any author who uses these companies should know ahead of time, that's where they stop being helpful. Their real money comes from milking authors through overpriced promotional "opportunities." The LAST thing they will ever do is to voluntarily make any attempt to actually promote your book in the interest of actually selling some and making their money that way.
My advice: ignore all the calls, and promote your book the way you want to. It will be better targeted and a lot less expensive. (I've been promoting mine through Facebook fan pages, with some pretty good results.)
In summation, use them for what you need them for, and then ignore them. (Like a really crass one-night stand.) And try not to get depressed about how author-milking has become the primary focus of the industry.