Bad After Sales Service - Incomplete Product Delivery

In August 2022 I bought a backup kit with N Energy 48v Lithium Battery for my customer. The battery came with no wall mounting bracket and it had nicks and scratches that were blamed on the courier. I've been chasing them for the bracket since. Now, they're coming up with silly excuses like the battery doesn't come with a bracket or the product description does not mention a bracket. The battery is described as a wall mounted battery. How can it not have a mounting bracket and they're saying that now that they're failing to fulfil their promises.