Recovered ****** phone

My Samsung S6 got lost or was ******. I received an email from Samsung, TM Electronics, to confirm whether I handed in the phone for a screen repair. I told them that the phone was actually handed in by someone who stole it or whatever, and they must keep it with them until I come and get it. Now they won't release the phone to me, because apparently they are bound to this person who brought the phone in. They say they are going to give the phone back to this person. This just doesn't make any sense. I have all the proof that this phone belongs to me. My hands are tied. I really don't know what to do now. The lady at Samsung is very rude and arrogant. I mean, the phone belongs to me. Just give it back. Or am I wrong. Any sensible person would know that this would be the right thing to do.