This is gonna sound stupid but how much bleach is too much? my hairdresser put some on my hair recently without my permission, it couldn't have been on any longer than 5 minutes. it was bleach so that my hair would go a light red at the roots, but instead it went really, really dark red which i dont like at all. My hair has been pre-lightened before but never full-on bleached,but now im scared to get the dark red lifted on top of the bleach...should i be worried? will it really mess up my hair ?

It depends on how much damage your hair has sustained. I don't understand exactly what happened to your hair. Was it naturally dark or was it dyed? And if it was dyed, was it dyed on top of bleached hair? You say the hairdresser put bleach on your hair without telling you, to achieve the colour that you wanted? Since it went dark you probably didn't leave it on long enough. If your roots were natural and you put a little bleach and lightened your hair a bit, I don't think it will be too much damage to bleach it again. After all you only left it on for 5 minutes.

I agree and most permanent dyes will lift you hair colour a shade or two anyway. If you've been okay with them it should be alright to bleach a bit more. If in doubt do a strand tes.