Advanced GM : Magical Security, how to fool magical security in AAA Options

[aspro]

Hi
I m an experienced GM and i m wondering about astral security. I can t find a way to penetrate a secured complex without triggering a magic alarm. If there s a spirit in astral form patrolling the area i want to visit, i ve no way to deal with it without being noticed. Because if the spirit was told to warn its summoner if it detects some intruder, it s impossible to stop it. My choices are :
- to banish it : but in this case the summoner knows it and trigger the alarm (i m wondering in addition if it s possible to banish a spirit in astral form as this operation can only be performed on physical plan)
- to attack it : but same problem as above.
- to jail it in a spherical astral barrier : but there s an astral combat between them and if spirit wins i m back at dealing with it ! and if my barrier wins the spirit is killed and its summoner knows it and trigger the alarm again
- to bind it with the spell manabind : no way to succeed with a spirit of force 6+ as i have to make 6 net successes TN 6 to put its quickness to 0 to immobilize it

I can t see any issue that doesn t warn the summoner and if the complex i sneak into is very secured like AAA i can let the security be warned or i m dead :(

Any ideas ?