Amanda Bynes -- Roommates Demand Money for Hair Dye Damage

Amanda Bynes and her parents are on the verge of getting sued for allegedly trashing the apartment where she's been staying.

TMZ broke the story ... Amanda was staying with 3 girls in West Hollywood ... one of whom was her hair stylist. The girls say Amanda went wild at times ... burning cigarette holes in the carpets, splashing blue hair dye on the carpets and porcelain sinks, and on and on.

The mother of one of the girls signed the lease, and she contacted Amanda's parents and demanded $1,500 to repair the damage.

We know Amanda's parents told the mother to pound sand, saying the girls knew Amanda was unstable when they allowed her to stay against the parents' wishes, so as far as they're concerned the girls assumed the risk.

One of the girls told us ... Amanda was like 2 different people -- sometimes she was sweet and quiet and then on a dime she would turn angry and rude.