Did not fully understand the exact nature of what is and is not working here, but I may be able to help you trouble shoot.

First, the switch for the brake lights is NOT your problem if any brake lights turn on

Second, the third brake light...wagon or sedan?

It sounds like, but I am not sure, that you are confusing running lights (taillights) with the brake lights...or fog lights if your car is so equiped. Put BRAND NEW identical bulbs (brand, wattage...everything) in the brake lights. Does the problem change or remain the same?

If it remains the same, use jumpers to wire the brake light directly from the harness to the contacts on the bulb holder (unplugging the harness is the easiest) for the brake light...don't forget the ground. If the bulb lights when you apply the brakes, the issue is the printed circuit board flexy thing...istall perm point-to-point wiring. This is assuming that you have already made sure the groud wire is intact and making good contact with the chasis.

If none of this helps, I would bet it is a failed bulb-out relay if you car is so equiped (which I am 99% sure it is). Other will chime in if I missed something.

Onkel Udo