Sent my car for a major service and the spark plugs were never changed yet I was charged for them

I sent my car (an Audi A4) for service at Car Service City in Jet Park Gauteng. They then called and told me what was needed to be done in the car, I told them to do just the service (oil change, oil filter change, spark plugs etc). Those people only did an oil filter change because the previous oil filter was black in my car, so when i came to pick up the car there was a white filter installed.

I then drove home to the EC then after around 800km of driving, my car suddenly didn't have power and it sounded funny. When I got home I opened up the engine and removed the spark plugs because I wanted to make sure they were fitted correctly as I was suspecting them, only to find out that the SPARK PLUGS WERE NOT CHANGED. the car still had the old platinum plugs because I explicitly told them to fit standard ones and not platinum ones.

I was very angry and disappointed and will never take my car there ever again and I advise car owners especially if you don't know cars that well to never take your car there, they will charge you for things they have not done to your car and say they have done them.