Comcast required new box, it didn't work and they refuse to make service call, keep rescheduling, Internet

My mom is 79 yrs old and Comcast sent her a new cable box and shut off the new one.  I tried hooking it up for her as well as my two nieces.  When she called Comcast, they told her it would cost $50. to come out.  When she explained the situation, they made an appt. but never showed.  She sent an e-mail to the corporate office.  Someone called her and assured her someone would be out the next morning and they never showed.  They said it was re-scheduled for the next day. Basically, they are a major company with plenty of customers, know that they have contracts sewed up with apartment complexes and there is nothing that the consumer can do about the problems except get extremelyth frustrated. It's ashame that companies have no customer service to begin with, especially senior citizens who are at there mercy.