My wife has Multiple Sclerosis, and is in a wheel chair. How do I get her the help she needs?

How do I get my wife the help she needs. My wife has M/S, and is in a wheel chair 24/7. Her main needs are to get a shower, put on the toilet, and get dressed. She has in-home care, but there are only a couple of girls that can take care of these needs. Is there a way to ask for a certain aide? Can someone be assigned to my wife that can take care of these things? My wife has a regular aide who takes care of her needs, but the other 3 days, or the fill-in days always seems to be a crap shoot on who the agency sends out. Can I ask specifically for a person? Who do I talk too, should I call the agency direct (We have discussed this but no satisfaction) or should I get your agency involved seeing if you could step in on my wife's behalf? Hoping you can shed some light. Thanks. cc