I had surgery on my nose to open up the passage ways and now the pressure is too high. I tried adjusting the pressure but when is gets to 17 it bounces back up to 20 and starts all over again. It will take a month to get a new sleep study and appointment with the doctor and I need to use the machine. I followed all the instructions to adjust pressure but won't let me go below 17. Resmed Series M Auto. Anyone have ideas on how to get these units to repond?