Air Service A/C & Heating

Corrected the horrible work done by a known AC company in St. Tammany.

The contractor installed the return box in what appeared to be a good installation. However, a day or two later I peered into the return (by removing the air filter grill from the wall in the hallway) and could see into the return box. It was then I noticed that the contractor had cut a square opening out of the box to align this opening to another duct, which was fine; that needed to be done. But in doing that cutting and connecting, he did not seal the exposed fiberglass material, which like loose hairs, now flap freely as the air passes by and moves through the system. There is a reason that fiberboard has a baked on sealant, to keep the particles from releasing. 
When I brought the above to his attention (a few days after the install), he said he would have someone come by and apply a sealant.  It took a few calls and catching him on the phone to get him to commit to the latter, but several days passed by with nobody showing up to finish the job. I called him again and said I would do it myself it he could tell me what kind of sealant (mastic) to use, as I had done some research but wasn't positive how to go about doing this, or even if I should. He said he would drop off a pail of the material, which he did.
This is not a bad company, per se, but it is not a good one. I had specific concerns, communicated them, and was willing to pay for work to waylay my concerns, yet the above is what I experienced. I am now contemplating having the entire box replaced with  the type I originally wanted, which will cost me around $500.  I could try to do the sealant application myself, but  to do so would require that I purchase a special ladder (~$200 or more) to get into the return space in my wall and extend it high enough (attic height) to do the work.  
If you know enough about HVAC work and have the time to watch everything this contractor does, then perhaps they might be ideal for you; but if you are an average homeowner who wants to hire a professional you can trust, this is not the contractor. I struggled to give them a C, but when I thought about the fact that they ignored my concern, a health hazard, they are lucky to get a D.