condensation/bacteria/mold in ventilation

There is a problem with the AC/Heating system. System doesn't drain properly, allowing mold/mildew/bacteria to build up. Filters get clogged with mold and bacteria. Smell is terrible. It is most prevalent during the change of seasons when you switch from using AC to heat and back. Type in "Volvo AC smell" and you'll find MANY other Volvo owners have the same issue. Volvo's solution is to replace the filter and spray disinfectant into the system. This only masks the symptoms, and does not solve the problem of the mold/bacteria forming in the system in the first place. Breathing in mold and bacteria is not healthy, and neither is breathing in disinfecting chemicals they use to "clean" the system. My understanding is that to properly fix the problem, the dash needs to be removed to get to the part. This is 8-10 hours of labor, so it is expensive to fix. I have contacted the dealer numerous times about the issue (still under warranty), and have called Volvo's "customer care" line to report the problem. They have declined to fix the issue despite knowing that many of their vehicles have this problem, and knowing that it is a health hazard.