Parts not changed at services for 8 years!

I bought my car new in 2011 and have been taking it for services at VW religiously every year. I have been taking it to different branches as in the 8 years since buying my car I have moved around quite a lot. I can not pinpoint a branch however what I can say is I have never gotten my old parts back after a service. Recently, May 2019 I took my car for it's next service. This time I did not take it to VW, The spark plugs that came out of my car was burnt at the ends and the oil filter was completely blocked and it had a date stamp on it that dates back to 2011. When I contacted VW they informed me that they have to change the oil filter with every service. Why in 2019 is there a oil filter dating back to 2011 in my car? Surely they can't still have 2011 parts laying around on the workshop floor in 2018? Since I am a 25 year old woman and have no idea what sort of damage this could cause to my car I handed over the dealings in this issue to my fiance as he has more knowledge about cars than i do. He was just told that I we have bought the car and we must "deal with the situation". Meaning they will not even apologize for not changing the parts since 2011! Parts that I have paid for! Parts that they have admitted should be changed with every service! From this day forward I will always ask for my parts back, I will never in my life buy another VW or support VW in any way. I will go out of my way to tell people my story and warn them against buying a VW. Note to any unfortunate people such as myself that owns a VW, ALWAYS ask for your old parts! These guys are mechanics, whether they work for VW, BMW, Ferrari it means nothing, They are mechanics and will always look for someone to take advantage of.