I worked for a tranny shop years ago and I swore that if it couldn't be fixed by a good conditioner and a little exercise fallowed up with a filter and fluid change by me, that I would buy a tranny to replace it with. A C6 is easy to rebuild yourself but with what I've seen in the tranny industry, what you got is what I put in the first line of this post. It fixed it and then a seal went out and they had to fix that. If they had rebuilt the tranny then it would have gotten new seals and they would not have charged you to replace a faulty one. I saw so much of this going on it made me sick and I didn't want my name part of it. There are some good shops out there, but I don't know how to identify them!