Mercedes A Class (2002) Wont Start..

[bn4com]

I bought a Mercedes a class with 12 months MOT from a week ago, however the seller advised it had a rattle on tick-over due to low oil, with a little revs and on driving the rattle stopped.
However after topping the oil up, the GF drove it and the revs went high, smoke came out the back, then the engine cut out.
After starting it again, it did the same, now the ignition wont even come on.
I've sourced advice off a few mechanics and got different answers.
The first hadn't a clue, the second believes its knackered (this i believe was an excuse for him not knowing an answer), the third made the most sense, believing it may be oil has got into the turbo and the turbo is knackered, needing a new turbo and oil and filter change.
I am annoyed as i believe the seller knew there was an issue and was hiding it, but due to the 12 month mot i believed it to be mechanically sound.
I don't know if this is the correct answer or if anyone has any other ideas/advice/ideas on cost or what work is involved as i'm no mechanic?
All responses are gratefully received..
Kind Regards and Thanks..

[baza]

I think you may have been duped, the MOT is not a guarantee of mechanical parts, only that of the time of the test the vehicle was road legal/

[sapelesam]

Do you know the exact model, and is it petrol or DERV.

[tonyav]

I also think that the turbo is the likely cause of the problem.
Seals have probably worn allowing the oil that lubricates and cools the bearings into the inlet side of the turbo.

[Hymie]

I would never buy a vehicle from a seller who admitted that the oil was low to the point of causing engine noise – I would expect the engine to seize.

If the seller could not be bothered to add oil (probably costing less than £5 to top it up) to avoid serious damage to the engine, what else would such a seller neglect on a vehicle they own.

[sapelesam]

Hymie, some people have very little understanding when it comes to cars, hence the belief that an MOT makes the car OK. If you can find a friendly mechanic to check a car over, you could save a fortune in the long term.

[Baldric]

It's a 16 year old car, what did you expect?