For the first day of tattoo maintenance, they should have told you to wait for one hour and then lightly rinse the area with diluted, non-scented soap and then apply A&D. You're only supposed to use A&D for the first two days and then switch to unscented lotion, applying only TWICE a day (anymore can ruin the tattoo). Did they ask you to sign any papers when you got it done? Usually these papers list tattoo maintenance somewhere on them. If not, and if they didn't make you sign a release form agreeing that you wouldn't sue them for infection/damage/etc, I would sue them.
It's possible that the tattoo artist who did your tattoo simply didn't go over the lines well enough (which would result in a dull, faded appearance), in which case you can't really sue (every artist works differently - yes it sucks, but that's how it is). Also, it's possible that you didn't care for it well enough because they didn't tell you how to (in which case you'll have to wait for it to completely heal - most artists won't touch up on a tattoo until 3 weeks after it's been done). They'll charge anywhere from 50-150 depending on where you go. Most tattoo shops have a minimum charge of 50, regardless of tattoo size. I had my last tattoo done in two sittings (the black outlining was done one week, and I went back 3 weeks later to have the color filled in - the tattoo artist wouldn't work on it any sooner than that).
Best of luck, and I hope you get your tat fixed.