Vitamin C Powder Review

Okay so.. I read online that using Vitamin C powder strips hairdye, especially red. So, I tried it because I have had my hair dyed red since this time last year and its kind of fading now into a light red/ginger/light brown color. I miss my natural hair and would really like to go back to it. So, I tried using this and im just going to say what I did, what it turned out like etc. 
I started off by putting the whole (yes the whole) pot of powder into a pot with the same amount of shampoo, so it was half and half. I used an old pot, like a plastic pot and got myself a spoon to mix the two products together. You can use any shampoo you want, maybe using a moisture shampoo that keeps hair smooth, this powder can dry it out. I then applied it to my hair like I would any shampoo, although it feels really grainy like a scrub! I got a carrier bag, like a Tesco, ASDA, Sainsbury one etc and put it on my head and tied it to the back. Making sure ALL hair was covered.
I waited an hour to let it soak, and rinsed it out. I appled conditioner after and rinsed that out.
The outcome - Well.. nothing happened. It went a lighter color slightly, but nothing actually happened, there was no major difference and I applied two of these 50 gram pots on my hair. I wont be doing this again and I dont really recommend it..
Lots of Love xxx