She uses older style hearing aids (she can't manage the newer ones). She can't hear on the telephone...only gets about 10% of the conversation even when I isolate words and speak slowly. We got a special phone from the phone company but it doesn't work any better. We don't know if it is hearing or understanding that's the problem because of her significant dementia. But she calls 7 or so times a day and calls continuously if I don't answer, but she can't hear what I say to her. What to do?