Liability

Generally, the parking facility is not liable for theft, especially if it is free of charge.
The parking facility MAY be liable to take reasonable measures to prevent theft. But, for example, a parking meter has no liability at all. If your company and its parking facility has some wrong-doing that leads to your car's theft, then you can sue your company. For example, your company may know many car theft cases happened in the parking facility but does not take any preventing actions nor to warn parking facility users.