Six or seven years ago, I installed a $25K audio/video/lighting system for a budget conscious client. In an attempt to save him some money, I came up with a design that missed the mark on usability and reliability - particularly on the audio side of things, where I used a motley collection of audio gear in place of a high quality matrix and amps.

While the system has basically been working since then, the overall user experience has not been great. For example, there are times when the client cannot get music to play in a given room. Sometimes he calls me and we work it out together. Sometimes he doesn't call and just deals without having music.

After a recent incident, the client asked for a proposal to overhaul the system. The main goals are to: a) simplify the user experience, and b) improve reliability.

The solution that I think would make the client 100% satisfied would cost around $5-7K without any discounting. Part of the solution takes advantage of new tech that wasn't available originally, but a good chunk of the solution is to redo what I didn't do well the first time around.

Here's the question: to what extent should I discount the part of the solution that needs to be redone because I didn't do it well the first time?

I know there are MANY details that I'm leaving out, but I'm curious to hear thoughts on how others handle similar situations.