Warning - Window World:
In my case this company didn't install all windows as promised because they made a mistake measuring them. Still, the entire invoice amount was billed to my Credit Card.
I didn't get any reaction to four emails and two phone calls. Only after the 7th try I was promised a partial refund. In regard of the remaining work at the unfinished windows: it was supposed to happen within two weeks, it took them five.
Windows World does not offer any discount and refers to their fine print that allows them 180 days to react. They also refuse to provide you with a written answer so they can't be held accountable. I would be very careful doing business with them.