without seeing a pic of it,a little redness around the tattoo where the saniderm was is normal, also could be a little bruising which is normal and will also go away, it will go away.
How exactly do you know this? It really goes against everything I've heard.
As @oboogie said, this isn't a site for artists to exchange tips, I'd suggest reading the rules. If you want to be a tattoo artist, talk with your own artist next time you get a tattoo.
Why would they admit they did anything wrong? What's the upside for them?
You're only about three weeks in and it takes up to eight weeks to heal normal tattoo. I wouldn't be surprised if that continued to improve for three or four months. Just keep taking good care of the skin, a little cocoa butter ever day, but not too much. You might even want to try some liquid vitamin E.