Does anyone know how to replace an ignition tumbler on a 1995 c220 Mercedes. The dealer wants to charge me $800 to replace is that normal. Help!!!!!

To start with, is the tumbler stuck & won't turn? If so then everything relating to the complete steering lock must be replaced..takes about 3 hrs to CUT out the old lock & then all new parts are required.

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I purchased a new key ad it unlocks the doors but won't turn the ignition on. Is $800 reasonable?