I have booked in my 2007 BMW 1 Series at a dealer for replacement of tensioner and timing chains. I have now been informed that the crank has worn out and needs replacement as well. BMW is asking around £1000 for this job on top of what is being done already. I bought this as used car with a dealer 1.5 years ago. It hasn't been serviced at any BMW garages. Should I expect them to change the crank for free of charge?