New sleep test

Hi, new to this forum. I have been dealing with apnea for a long time, tried CPAP (too much gas in stomach) and BiPAP (sore sinuses). I then just toughed it out for several years using a mouthpiece, elevated bed, etc. Continued poor sleep is now affecting my health, so I now want to try an ASV device. My doctor says I have to start all over again with tests for CPAP and BiPAP, even though these were tried before and I still own a CPAP. I am now on Medicare. This seems totally crazy, and I want to try an ASV as soon as possible. My last sleep study was done in 2015. I don’t see why I have to start from square one, spending weeks/months with devices that don’t work, instead of testing an ASV device now.

I checked with Medicare about the need to start over. They said it is up to the physician and the “provider line”, which says to me that my doctor has leeway that is not being taken advantage.

Does anyone have any insight into whether what I am being told is accurate?

Also, is there any reason that a further test could not be done at home? My sleep quality in the clinic does not approximate very well my sleeping at home.

Many thanks