No Brand Accountability

I recently serviced my vehicle at VW Autohaus Centurion were I found out after the major service that items like spark plugs and air filter etc were not replaced even though I was assured these items were replaced. I reported the incident to VWSA with proof of *****ulent activities and expected them as the parent company, the company I purchased my car and extended warranty plan from to hold their service centres accountable, extend my service plan as I did their work for them after all if I had broken down due to their negligence, these costs would have been for my account. I was told the service centre is independent from them even though it has VW name and if it happen to them personally, they would avoid going to that service centre in future. VWSA took no responsibility or accountability in ensuring my and my vehicle's well being. Their Customer Centre rarely returned calls, no updates and made it my issue to follow up on. No official response to the questions raised and response to the complaint lodged.