("boyfriend" euphamism for pimp, I'm betting)
My guess is the phone belonged to her "boyfriend", and he cancelled service when she told him she left it at the house. The boyfriend dropped her off at the house, no doubt she was supposed to call him to pick her up. But she didn't get paid, and remember how she refused to get out of the car at the Kroger? I bet she was scared to death of that "boyfriend", and made up the rape story as an excuse for not bringing home the dough.
Armchair sleuth, at your service.
I think you are 100% correct, and the pimp -- er, boyfriend -- did the beating because of the shortage of money.