Bridesmaid Problems??

Hello,
I am having a similar problem with my bridesmaid who has been my good friend since I was 6. She had told me for the past year she was definately going to be in my wedding. She was also asked to be in two of my other friends weddings which were a month apart. She has a 2 year old daughter who is supposed to be my flower girl. I have been telling my bms for weeks that we were going to look at a dress today. My BM who has the daughter said she might not be able to because of car trouble. Turns out she didnt have a ride so I offered her to drive her. We get to the shop and find a dress I absolutely love. The shop would like a 20$ deposit to order the dress and she cant come up with it until end of January for a deposit. Then I get a message later saying she"ll have to let me know if she can be in my wedding. She cant come up with the money before the end of January. I offered to help her pay at least 100$ of her dress. She hasn`t even returned my message. I don`t know what to do!!! I would feel really upset if she wasn`t in mine and was in my other two friends weddings which I am also. What should I do?