Yes, it seems you really have a rare model...
This was only available in the 1998 model year for U.S.-market vehicles.
{Comfort control unit}
ECU adjustment (USA, models from 9.97 to 05.9

.
Select STG 46 (Comfort Control Unit).
Adjusting the ECU -> Function 10.
-> Channel 03 (Automatic Lock/Unlock)
The vehicle locks at a speed of 15 km/h (0 = off; 1 = on) and unlocks again when the ignition key is removed.
-> Channel 05 (unlocking horn).
The unlocking is confirmed with a short beep (0 = off; 1 = on).
-> Channel 06 (locking horn).
The locking is confirmed with a short beep (0 = off; 1 = on).
-> Channel 07 (unlock blinking).
The turn signals are activated when the lock is disengaged (0 = off; 1 = on).
-> Channel 08 (locking indicator blinking)
The turn signals are activated when locking (0 = off; 1 = on).
The remaining errors, such as unlocking the car randomly, etc., may be caused by a faulty wiring harness, kinks, etc., which are common problems in Passat/Golf models.