Warranty on recently bought used car?

Hi there this is my first post here, any help would be greatly appreciated.
Bought a used car a week ago from simi dealer, my first time buying a used car, and apparently due to my ignorance i didn't check the engine as good as i should, few days later i check the engine carefully and i see some (old) oil under turbine.
I took the car to the dealer, he gave the car keys to his employee, supposedly to take it to their mechanic to check it, comes back a few minutes later, and he just gave everything a good wash, and dealer didn't say anything to me about the issue, only asked me what was wrong, and then tried to convince me its normal for 9 year old car and i should give it a watch over the next days and i should come back if i see more oil.
After driving around 150km that day, i saw that the leak is not old, but keeps going, and its through the turbo actuator. Making a little research online i saw this is typical problem for this diesel engine (1.6 hdi 110hp diesel) and its causing turbo failure, and eventually engine failure after.
So it looks like its a very serious issue, probably unsafe to drive that way, and expensive enough to fix (turbo fix/change / engine cleanup n all), and probably dealer knows all about it and im sure,according to his behaviour so far, he wont ever try to fix it, instead maybe he will do some work to give a temporary solution, so it will give it a go for few months to avoid warranty.
The dealer gave a written 3 month engine kai gearbox warranty .
So im trying to find out what are my best chances, as the car is only bought 10 days ago.
Should I get the car to a garage and ask them to check it and write a report of what they see so I can use it to fill a simi complaint form and request my money back? Is that gonna work?
Whats the best i can get out of this situation?
Thanks for any help in advance