Exactly the same happened to me the other day. I use a hair dye I get in the States called Natural Instincts (by Clairol). I just use the 28 washes one in Clove just to enrich my hair colour a bit. I decided to get something more permanent so I got Nice n Easy (Clairol) in medium ash brown. My hair went black. It was the day before I was going to work. I went to boots and got Decolour (by the same guy that does B4). It went bl00dy ginger! By this time it was about 10.30 at night. Thank God for 24 hr Tescos. I went back and got the Nice n Easy light ash brown and stuck that on. It went back to pretty much how it was in the first place. Beware, if you try to recolour it, you`ll need something much, much lighter than you normally need. Apparently, washing the hair first a few times with something high ph like washing up liquid opens up the hair shaft and makes it easier to wash out dye.