OK, what people are talking about is that you can take 2 items per cabin to Guest Services to be signed by the characters. You complete a form saying who you want to sign it (princesses, all available, classic characters, etc) and giving any other details. You can take anything--t-shirts, pillowcases, photo mats, hats, vinylmations, etc. IF you send markers with your items, they are supposed to be signed in your markers. If you don't send markers, they will be signed in black sharpie.
My guess is that in the process, OP's markers got separated from her items. It is helpful to write on the form "Colored markers enclosed" or something like that and to package the items and markers together.
As to how many character signatures you get--it varies with the length of your cruise and the number of items that are turned in to be signed. As noted, it is free and in my experience, they do make a serious effort to meet your specifications.
Sorry that OP's items weren't what she wanted/expected. I'm just guessing the package didn't get to the characters intact.