Multiplex development

I hired Multiplex Development LLC for two projects, beginning in Aug, 2016. The first was to remodel the kitchen, enclose the carport, replace all windows, and fence in my back yard. Cost was over $30K. Project was completed but window installation was extremely poor. Most windows leaked air between frames and sash. Also, kitchen backsplash wasn't trimmed to match the original backsplash. Shawn Spears promised that both issues would be corrected while they did the second project - add a sunroom. Cost was originally estimated to be over $20K. Multiplex billed me for cost excesses that were due to their miscalculations and poor work. Original projected completion date slipped repeatedly due to failed inspections and rework required. In June, Multiplex finally walked off the job and I had to hire other contractors to finish the job and correct Multiplex poor quality work. In the end, my out of pocket costs to complete the project, and correct problems from both projects, was well over $6K.