Quality Bad. Attitude worse.

I have a 2012 Jetta 6 which I purchased new and have been the only owner. I had it under mainenance plan. Within the first 2 years, 3 out of the 4 door locks gave in and needed to be replaced. The last door lock over the next few years would often make strange noises when locking and unlocking like it was struggling. Occasionally it would fail to lock. Each time it would go for a service I would ask them to look at it. They would say it was locking and unlocking fine despite the noise and they gave it a cleaning and it should be ok. Now that the car is out of maintenance plan the remaining door lock gives in and refuses to lock just like all the others did. I have never replaced a door lock in my life and now I have replaced all 4 in one vehicle (3 within 2 years and 1 making strange noise). Now to any objective person this would indicate the possibility of a potential faulty product or possibility a bad batch. Now a new door lock costs a ridiculous R6800 to replace. I contacted VW SA to look into the issue and cover part of the cost as a goodwill. They have all the records of the door locks actually replaced and the fact I had asked the other lock to be looked at of numerous occasions while under maintenance plan. They came back and simply said it is 7 years old and so outside of any goodwill time period. So even though all these door locks failing strongly indicates a faulty product or bad batch, they are not willing to contribute even a single cent towards the replacement. Instead they will make a profit out of me having to replace their defective part. This attitude of VW has absolutely disgusted me.