bidorbuy not investigating issues , Buyers buy incorrect items and sellers must refund and take the loss because buyers are clueless or changes their minds

I sold a surveillance hard drive that is in 100 percent working condition. The buyer is wanting to use this 4tb in his home theater system . His pc recognizes the drive in RAW format so it just requires a format. He doesn't know how to do this. I requested him to put it in a dvr to format it and record a video in order to prove that the drive is not working. He is not willing to do this because he knows the drive is working. Bidorbuy now expects me to refund him. I must refund him because he purchased the incorrect drive for his needs. Why must i refund a working item because the buyer is clueless and purchased the incorrect item. My performance rating on bidorbuy is 97,98 percent . The buyers performance rating is 79 percent. Surely that is a good indication of who is trying and who is not. This same guy orders items and sometimes pay and sometimes does not pay . but i must refund him . Bidorbuy did not even investigate and sided with him because the agent is also clueless. Tells me that you cant use a hard drive the wrong way because all hard drives are the same and will work on any machine. This platform is going down just like the rest of the country. It the same as buying and trying to fit a diezel engine in a petrol car and then expects a refund...