2005 Jeep Grand Cherokee drivers window glass keeps breaking

My drivers window glass broke the other day. I called a repair service and he came out to replace the window. He told me that someone had worked on the window before, but he put the glass in and it worked like a charm. Even better than before. The next day, I rolled my window up and it cracked in the exact same spot. I called the glass company and they told me that it wouldn't be under warranty since it sounded like my regulator was bad. Wouldn't they have seen this when the glass was being replaced? Or could it be something else. I am now out $300 and change for the replacement glass and must spend more to get another window installed. Help please!