This is the most important lesson learned from my venture (and adventure) into self-publishing: do-it-yourself really means doing it, all of it, entirely by yourself. Anything done for you will be costly. So if there are mistakes, if things don’t turn out as wonderfully as they appeared when you imagined them, then, as the old blues song tells us: it ain’t nobody’s fault but my own.
The “publisher,” or the printer, has no interest in or investment in your work, your book. You can have written the same sentence — I am just a damn fine writer — over and over and over for a few hundred pages, and they will happily print it for you.
If there are flaws in the cover that you did not notice, they certainly will not notice or correct them for you. If there are typos you did not notice, they certainly will not notice or correct them for you. If a page is printed upside down and you did not notice, they certainly will not notice or correct it.
I repeat: the vanity publisher or printer for self-publishers has no interest in or investment in your book or in your as a writer. You pay them to do various services for you. The end result, the quality of that product, will be determined entirely and solely by you. Period.
That is the critical difference between mainstream traditional publishing companies and vanity presses. The first invests in you as a writer and has a vested interest in both your success and the quality of your work. The second does not. You are on your own, brothers and sisters.