cannot save

Is there a way to save objects to business data without the Row was updated or deleted error?

I have a problem since a few months, tried many things to counter this error, but i just cant make it work.

The error: javax.persistence.OptimisticLockException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)

I know why this keeps happening, i have a Client business data object, that has a list of Car objects, and the Car objects have Services.