Paid for my vehicle to be fixed, it was never fixed instead I am asked to pay more money !

I purchased my vehicle in 2019 at the VW Princess Benoni great north, I have been servicing there and have never missed a service. I started having issues with my vehicle I sent it in and was quoted 13k for it. I paid for the service got back my vehicle and I was still encountering the same issue, I sent the car back for them to have a look instead of fixing it they quoted me 36k to fix the same issue that I had initially bought the car in for , I don't understand how I can be quoted twice for the same issue which they have failed to fix in the first place and at this point I don't even know if they even did any work on my car when I first brought it in. I am really disappointed and believe that they are ripping me off.