2008 Chevrolet Other

I brought a diesel Chevrolet captiva 2008 from a dealer but as doon as I brought it home it started to leak oil heavily and the mechanic told the engine has back compression and needs a complete overhaul.I told this to the dealer and he told me he would get the car repaired but give it to me. But the problem is he is getting it overhauled at a cheap ass mechanic.I feel like betrayed n cheated. He told he is putting a new turbo. Is this enough to control back compression in a car? If not what else needs to be changed sorry for long question but I will be really greatfull if u reply.
January 5, 2013.

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