Rach there was a massive thread on this which might give you some comfort. Scroll down and you will find it. Good luck. ps my DD1s room is a tip. Mostly I just sigh and shut the door but I have gone in and thoroughly tidied which really annoyed her and now she does do it if I suggest I might have to do the same again. The personal hygiene thing is a bit worrying could she be depressed? Anyway have a look at the thread below there were lots of horror stories and good advice.
My daughter is 16 years old and refuses to take care of her personal hygiene. It has been going on for at least 3 years. She wears the same clothes night and day, refuses to shower and smells really bad. Her room also resembles something from one of those hoarder programmes. Bath time was always fun when she was younger (songs, games etc). I have tried talking to her gently about it, discussing the health implications, buying her 'branded' toiletries but nothing has worked. I have just tried point blank telling her to go in the shower, which resulted in her telling me to "f* off". Any other suggestions would be greatly appreciated.