Passat Security/Immobilizer issues.

The gist of it goes like this. I bought my passat recently and the owner was
straight with me that the locking system was annoying to the point you have
to lock it in a certain manner or the security system kicks in making the car
unable to start. The alarm doesn't go off it just won't start and the lights will
just turn on in the dash as it shows me it still recognizes the key since it
doesn't reveal the "I don't recognize this key" emblem on the dash (if it even
has one like I've seen on other models). If you lock the trunk then the
security system kicks on and won't let the car start either which gets irritating
since there is another special routine you have to do. It goes like this, I got 2
keys from the previous owner one being a newer one from the dealer and
the older original key. The original key works with locking and unlocking the
doors and only that key can lock the trunk, but the key won't deactivate
immobilizer in the passenger door (and the deactivate w/e only works on that
door). The newer key works on deactivating the problem and
unlocking/locking the doors but the alarm gets set no matter what so I have
to walk to the passenger side door to disengage it every time I lock it or give
up hope on locking it. Is there a possible way of completely just deactivating
the security system/immobilizer so I can lock my car in peace or am I just
gonna have to drop my money into going to a dealership to fix it? (Also I do
not have a FOB but I do plan on getting one when possible).