Garage Door Maintenance

We called a garage door company because the garage door system started sounding as if it was straining. When the technician came out, he advised me that he adjusted the height of the garage door motor and adjusted the bracket that connected to the garage door arm.
Most recently, the bracket connected to the garage door motor arm was pulled off the garage door causing the middle of the garage door to collapse severly. According to the technician, the garage door panel became caught on the ridge of the garage frame. The result was that the garage door collapsed from the tension of the motor arm pulling on and eventually detaching from the bracket. 
After speaking to this company, they want to charge us over $800 to replace the door. They said the door was damaged due to natural wear and tear on the door and/or because someone bumped into the door (which did not happen).
Before the company adjusted the garage door, we had no previos issues regarding the door's hardware.

Does this company's processes and assessment sound right?

So the damage happened after they adjusted the door? It could be a coincidence that it happened after they did their work. You don't mention how old the garage door & opener are and what make/model they are. If the technician had to move the operator up & adjust the operator bracket it's possible they weren't installed properly to begin with. If that's the case it could definitely shorten the life of the door & opener.

It also doesn't sound like there is a u-bar stiffener or strut attached to the top section. Without it over time the center of the door will become weak. Every door that has an operator should have a strut on the top section to help strengthen the section and keep it from cracking or buckling in the middle.

Yes we have a U bar stiffener   Our door is 14 years old aqnd opener about 3 years old