Hi Lisa
It is common that diverse problems arise among roommates in the daily life.No doubt,it is fairly important for us to get on well with our roommates.I would like to offer you some advice.Maybe you should try to have a talk with Rebecca again,telling her that what she does affects your daily life badly.What is to be attended is your tone.Talk to her friendly and politely.Make her notice that she really does something wrong,Besides,you could ask the other roommates for help.Unity is strength.All of you talk to Rebecca face to face.I believe everything would be better.Wish you the best of luck.
Yours sincerely
Li Hua