Worst Car service experience ever!!!

I requested a service quote from the North End Branch in Port Elizabeth, providing them with my vehicle make and model as well as my VIN number in order for them to give me a quote specifically for my vehicle. I received a price and a list of things that gets done on a major service. I took the car in and when collecting it I noticed that the invoice only has oil filter, oil and air filter on but the price remained the same. I enquired about the spark plugs not being changed as well as the fuel filter as this was in the quote I received. I got told that I have platinum plugs in my car and they only get replaced after 120 000km which makes sense, the fuel filter apparently sits in the tank and is a high pressure fuel filter, and they don't change high pressure filters. I then emailed the owner and told him that seeing as I haven't received everything I paid for I want the invoice to be adjusted and get credit. The owner was clearly upset and told me that prices are fixed by head office and that I must take it up with them. He also added that the same service would cost 3 times more at a Mercedes franchise. To be honest I am totally disgusted about the service I received, besides not getting what I paid for, the oil on my car wasn't drained properly and you could see it is black after driving only 20km. my drivers side carpet was full of oil, meaning that they stepped into oil and into my car. The car wash was done have and the engine bay was cleaned with oil to make it shine. My license disk holder was ripped of and laid on the dashboard, not sure what the purpose of this was. I am sorry but I expected more, if you cant give a decent service rather close your establishment. Head Office is just as unhelpful after numerous emails I quickly realized they don't care. Stay away from these glorified backyard mechanics