TFT Unit bug that erased my tier 2 vayne and her items and replaced with a permanent enemy rengar

Had a Vayne that was tier two when coming back from the second shared draft that had rage blade and rapid fire. I got a rengar from the draft cause he had giants belt so I could get a titantic on my vayne but when I sold rengar to get the item, he replaced my vayne and was an enemy rengar that attacked my units and lost my items. It's already annoying enough to lose ranked TFT games because of horrendous rng but this is just entirely unfair.