The white bit described as "butchered at the factory" is a spacer/seal to position and make the lock waterproof it is cut away to prevent it fouling the lock and has been trimmed at fitting time to make sure it does not foul.
Not pretty to look at but will not be the problem unless it is either too thick or thin.

Have you got anywhere with the dealer? Usually the threat of legal action focusses the mind. A Solicitors Letter to them might be the cause of action to take and make sure you include the cost of reimbursement in your costs