sorry about this mess your in, but quite frankly it has nothing to do with the badge stuck to the front of the car
this is a high performance diesel engine, they are very complex, efficient and powerful and at the end of the day you have to pay for that. Regardless of the badge all types of high performance diesel cars are very expensive to fix, unless you can do it yourself.
after 3.5 years with my mjet im not sure i would by another diesel either, however the newer petrol engines with all manner of electronic valves and variable do das could be a nightmare in the future too. tough one, hope you sort it