Taxi E-Class w212 200 cdi Engine damage at exactly 200,000 km

We have a very big problem with Mercedes Benz , maybe one can help us to advise , about 4 weeks ago our limousine taxi Mercedes E-Class 200 cdi Blue has a motor damage at a run performance of about 200 thousand km since the vehicle is still warranty or 17 months old we have been informed , that the defect engine is sent to the factory for inspection (can take about 3 months so of Mercedes the statement ), the vehicle has complete service which was maintained by Mercedes e, the new engine should be delivered in 3 weeks in the workshop , today is day where the engine is installed (all good and beautiful ) now the contract workshop means that we should pay a safety from us of about 50% …thousand € , until the old defect engine is checked . we ask ourselves the question ??? why should we pay the new engine whether the vehicle is still in warranty . 24 months +4 months for taxes PS: a plastic gun (guide) is at the top of the S tirn chain broken off and has spread in the engine up to the Simmering rear (between engine and grated) which has been shredded from the inside (oil leaks) .