Inmates are basically the property of the jurisdiction they are held by and there is very little people on the outside can do to effectuate change on the inside. We have of course heard of stories similar to what you are referring to. But, we would caution you to not take everything your inmate says as 100% accurate. Inmates are notorious for currying favor from their loved ones with stories of abuse - amplifying your imagery of jail life. This causes you to want to send more money into their commissary, etc. You have to be careful to measure what they tell you and use good common sense. There might be some bullying that occurs especially in the beginning but this does not go on and on. Plus, corrections officers are not looking to get tagged with abuse stories on social media.
But, if you are convinced there are serious issues occurring, you can start filing complaints with the warden, the chaplain and even your local councilman. The caution we would warn is that with all your outside pressure you might cause more pressure on your inmate - and that is not the result you are looking for. It is a slippery slope to be sure.