Hampton Bay is a Home Depot brand and made by various manufactures in China. So unless you travel to China the only place to get parts is HD. But you may be able to retrofit a down-facing light from another manufacturer. The wiring is going to be bascially the same, the connectors are probably not, but you can cut those off and wire it directly. The fixture will be attached to the bottom of the light fixture and you may need to drill holes and bolt it on. The problem is getting access to it. But if you installed it I assume you can get it back down. If that is too much you may be able to get some screen material and fashion a cover, but that will retain heat. I assume bulb replacement is a pain too at that height. My old place had a two story stairwell with a hanging fixture. The only way for me to replace the bulb was to use a long stick with a hook to grab the fixture and pull it to the balcony and stretch over the railing and replace the bulb. It sure was a dusty fixture because it hardly ever got dusted!