Unit will not keep connected to SXM

When the Forester is powered down, the unit drops SXM. This began when the channels were realigned. We can do a refresh , have service, then service drops off when key off. Subaru rep says it is a Toyota unit, they cannot erase channels, must put something in on top of something…..OR do a complete erase. We did that, but the first 10 channels do not erase. So we filled all those with AM or FM stations. ALL the other presets are vacant.
I am told that all units have (a wire plug) with 1. Ground. 2. 12v switched lead from the ignition. and 3. a CONSTANT 12 volt lead. If a unit is removed (or stolen), when unplugged therefore the unit will lose the constant 12 volt lead. This is so a thief cannot simply unplug it, remove, then reinstall or sell it. I understand. However, what we are experiencing seems very much like this. (The switched 12 volt lead is ok. Subaru says if there happens to be any presets still to a now no longer used Channel, it will also behave this way.

VERY FRUSTRATED…we think it has something to do with the Channel Realignment done by SXM. We have paid for lots of months with NO SXM radio, only AM/FM stations. Please help!