Paying for services but nothing gets done on the vehicle

I sent my VW Golf 6 GTI Edition 35 for a major service in April 2022. Firstly it cost me an arm and a leg, nonetheless I paid for the service. Secondly, when i received my vehicle back it was mis-firing, so I took it back about a week later but I called the Sales Consultant to explain to him what the issue was the next day. When I took my vehicle in (the week after the service) the technician had to see what was happening, so I took him for a drive. When we got back to the workshop he plugged in his computer and mentioned it was the Lambda Sensor that needed to be changed (I was informed it was 1 sensor). Nevertheless I had both sensors replaced last week (25 May 2022). Once the sensors were fitted (by my own mechanic) I still had the same issue. The coil packs seemed to have been gone on cylinders 1,3 and 4. I then replaced them with Audi R8 coil packs on this past Saturday (28 May 2022). Upon taking out the old coil packs it was noticed firstly that the rubbers inside the coil packs were burnt out and also at a point melted. Secondly, when the spark plugs were removed (after much difficulty of getting the burnt coil pack rubbers out) the spark plugs were old and were not VW spark plus, they were Bosch. Does VW use Bosch spark plugs? This was a major service that I sent the vehicle for in April 2022. That in turn brings me to my next question i.e. What was done on my vehicle? Was anything changed? Why did I pay so much money for nothing to be done? Are consumers being ********** in broad daylight by reputable dealerships? Quite pathetic service which I am going to take up further!!! I have been messaging the Sales consultant the whole of last week (between the 23 and 27 May 2022 and he didn't even have the decency to respond. Spoke to Katlegho the Service Manager this morning at around 8:30AM (30 May 2022), and he still hasn't come back to me (now 10:40AM).

Do I claim my money back or do I take it up higher and fight for us consumers?