Service center damaged my auto

Is there a law which states that an auto service company must return our vehicle in the same undamaged condition as when we left it in their care? We had minor (non-engine) service work done & the auto was returned to us w/ engine damage. We assume a technician must have damaged our car with rough driving. He only admits to performing a test drive after installing a part. They're trying to pretend like the engine damage is a mystery. We don't have any proof other than their estimate didn't show any need for engine work before we left it with them. After they damaged it, we took it to a dealership & it required over 3K of engine repairs to bring it back to the functional state it was in before they damaged it. How do we recoup our 3K? The billion-dollar company's cust svc. people said we're accusing them of a criminal act, thus we should sue them 'cause they're not volunteering any accountability & our auto must have spontaneously broken while on their property. This is obviously hard to swallow. Any advice would be great!!

Based on what you say here, you could file suit against them (or at least threaten to do so) in small claims court or in regular court; filing in small claims court is easier and requires no attorney...you could try to collect all of the costs and damages that you suffered due to their behavior... You may also report them to your state attorney general's office.