FedEx They ruined a week's worth of shipped milk for my baby and refused to refund the most expensive component - the cooling box
FedEx shipped a week's worth of milk home for my baby - $100 for shipping, $200 for their proprietary single-use cooling box. The box arrived open and after a lot of complaint work, they refunded the shipping and denied the box cost - this box that was made useless by their handling and has no value for reuse.
Less surprising that after all that, the complaints inbox is either ignoring me or asking repeatedly for repeat info submission on the same email chain.