I understand what you are saying. My DME makes more mistakes than they get things right, at least so far. Even my insurance company is coaching them on their billing practices.
About filters, for me anyway, I get 2 per month so I don't get overly concerned about how thin they are because I change them midway through the month.
After the first month with my S9 Autoset I looked at the filter and it was as clean as when I got the machine. A month later it was still clean. By the end of the third month or so the filter looked a little dingy, so I threw it in the washing machine with a load of clothes. It came out perfectly clean. It has been over a year since I got the s9 Autoset and I'm still using the same filter.
I must have really clean air.