Uhhh...... NO!!!!! And let me re-emphasize that....
NO!!!
Sorry, but they messed it up, you owe them NOTHING! In fact, they'd be lucky if they even got to finish the job, given your description of their work. If it were me, I would have fired them from the job after they replaced the damaged equipment, paid them for what they had already done and hired another REPUTABLE company to do the job on MY terms. I'm not a particularly mean-spirited person, but when I'm the customer...I expect to get what I'm paying for, and I don't expect to endure incompetence.
