Poor quality locks on VW caddy doors

Constant problems with VW caddy doors. I bought a new VW caddy panel van in 2019. I have had the following problems with doors: Central locking not always opening doors. Back door not staying open swinging closed. The above two problems have been brought to the service team attention at VW the Glen when servicing the vehicle but still exist. The latest problem that started a couple of months ago is the sliding door not locking, I have to lock it manually by opening the sliding door and pressing a button. When I reported this at a service in late November I was given a quotation of nearly R9000. I feel that this is unfair as I have owned several vehicles in my life and never had one issue with door locks. I feel that the locks on this vehicle are of cheap inferior quality. My contact details : Gary Wilder *** Vehicle registration JF60GKGP