Bad Customer Service Experience

I recently took my car for an oil change at VW Upington and it was inspected upon arrival. When they were done with the service and from the wash bay my car came back with a broken windshield.

The lady who was assisting me told me to contact my insurance and they will pay the excess. Because i recently had that windscreen changed my claim was not approved.

VW is now refusing to pay for the windscreen they damaged. Where should I service my car now if customers are being treated like that?