Your VW's door lock protects your vehicle and your personal possessions by preventing unwanted intruders from getting into the vehicle. Your door locks are also the first line of defense in keeping your vehicle from being stolen. Should your door locks fail, you run the risk of not being able to get into the vehicle, and you definitely will have a hard time securing it against being raided or stolen.
GTI, CC, and other VW model door locks do not commonly fail on their own but can be broken under ordinary circumstances. Some times the key itself can damage the inside of the lock, and if someone tries to break into your car, that could also damage the lock. Even an innocent act like a child sticking an object into the lock can cause it to lose function.
Should your door lock for VW become damaged for any reason and needs replacement, genuine Volkswagen door locks are the best option for replacement. OEM VW locks are manufactured to your vehicle's exact specifications, down to the very smallest parts. They are also the best quality for long term reliability and use.