Terrible after sales service at William simpson

I bought a pre owned car (Jetta 6) at William Simpson in September 2017. Shortly after taking the car home, I noticed a smell, oil or petrol and I alerted the sales person and pre owned sales manager immediately. They advised me to bring it in which I did. The manager saw what looks to be an oil leak and said they would have it fixed easily. Well it's been 7 months and I am still sitting with a car that stinks. I have taken back the car for them to fix numerous times and each time I am told they have fixed it. But the minute they drop off the car I can smell it. They have tried to convince me that its the outside smells coming in, as if I am not an experienced driver. Having had a car since I was 18, I know a car should not be smelling like petrol or oil. I have asked since the beginning that they need to sort out the smell. On all the times the car has been returned to the dealership and they have had there mechanic team working on it, I have not been given proof of what has been done, only told. How do I know it has been addressed. So now they have finally agreed I can take the car to Barons myself to have assessed but they will only pay Barons depending on what the outcome of the report is. I flagged the smell issue with them from day 1, something that smells like oil or petrol, it is not for be to make a diagnosis, there mechanics team should do the proper diagnosing of where and what the smell is. I am frustrated, I pay the car every month, and yet I have had to take it in 5 times or more, I have honestly lost count.

In the latest incidence the driver drops the car off, I start it up, smell the smell immediately, I see 'sweat' on the engine and I am asked isn't that normal. HOW??? I am not a mechanic, but I know an engine must not be wet and a car should not SMELL... like anything!