By appearing in television, she has allowed the public to know that she can not speak properly and will loose the support of the public. This is very important in a case like this where the banks are claiming that she is not competent to do her job.
It would have been clear to those who first interviewed her for her job that English is not her first language. She doesn't appear to be stupid to me from her TV interview and certainly seems more focused than Palin who was accepted as a VP candidate for the entire US by almost half the population.
Junior bank employees are poorly paid and cannot be expected to be excellent orators and rocket scientists.