Similar happened to me about 6 years ago, before I took up hairdressing. No one could understand it as the lady used a cap for bleach highlights. I am a base 9 with golden tones so god knows why they used bleach, i did tell her I didnt want bleach blonde. She left me under a dryer for more than 20 mins while she went to do someone elses hair, no idea on the peroxide strength, but I'd imagine it was a high vol one for the damage it did and the time she left me there. I started to feel a burning sensation on the top of head right on my parting area, I told her and she told me that I would feel that, EH?? I was practically told I had ringworm and allsorts to defend their side.
She rinsed it all off and my hair was cotton wool. I had burning sensations in 3 places, like a triangle dot to dot. The 2 smaller burns healed up but the one on my parting area scabbed over and dropped off with a clump of hair. I was told it may grow back and had to have it dressed for a while. 6 years later I have a bald patch the size of £1 and have had to opt for a side parting to keep it covered. it is a nightmare when in the sun, easily sun burnt so have to keep it covered or wear my hear back.
I am left with a delve in my head where it is.
Hope it does grow back as I know how you feel.