Hello and thanks for trusting me to help you today. I am a licensed diagnostic and repair technician, I look forward to working with you.
I absolutely would not expect a crankshaft to break. This would be major engine failure, and with the millage of the vehicle, it certainly would not be expected. A crankshaft will usually last the life of the engine and even when it has excessive wear and tear, it can be re-ground and re-used. So for it to break is a major fault. With a modern diesel engine, providing it has been serviced to the manufacturers specifications it will do half a million miles before i would expect to see any major internal engine wear.The fact the shaft has broken would point to a manufacturing defect, wear and tear on the bottom end of the engine is caused by oil starvation, or over-revving, unless the engine was pushed well beyond its limits regularly or run without oil this type of failure would not be classed as wear and tear.
My best advice would be to have this inspected (of not already) By a Volkswagen main dealer, and make a phone call to VW Customer services, explaining everything that has happened. They will work with the main dealer to find out what has happened and often will help with the repair costs. Its important that the car has main dealer history for them to help in any big way but they are generally very good to a loyal customer.
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