Penny for Your Thoughts

She's picking on Penny and I don't know what to do.
Jenny is in her mid sixties, a bit of a kid by our standards. I did the assessment myself and we got on. She has had a lot of ill health and, though she disguises it well, there is a definite problem with her short term memory. I am a bit perturbed by a long and rambling tale she tells me about a family feud involving several siblings, it seems at odds with the friendly open demeanour she has shown up to this point. She tells me about her daughter, Beth, at length though. Beth has a hairdressing salon in a town about ten miles away and is a loving daughter who has asked for some help for her mum while she is at work. Jenny has been having a lot of falls and she wants us to help her with meals and personal hygiene - simple stuff to make sure she is coping.
Penny is one of our youngest carers. She is only nineteen and she is full of fun, a bit giddy but a thoroughly nice girl with a real knack for the work. She tells the clients to call her Twopence because there is too much of her to be a Penny and she demonstrates her karaoke skills while she strips beds and empties commodes - she is a live wire and they all love her. She lives in an out of the way bit of the area and she does the hard to get to calls near to where she lives. The people she goes to would be hard to cover without Pen, she is an asset.
Things seem ok at first. Pen says Jenny is enjoying the help and seems better. We record what we have done at each visit and Pen makes a note of what Jenny has at each meal. The first indication of trouble comes when she notes that she couldn't find any fresh bread to make the sandwich Jenny had asked for, Beth leaves a note saying that there were fresh rolls in the bread bin and Pen should open her eyes and while she is about it should get someone to teach her to make a proper cup of tea. Pen is upset but I jolly her along, these things happen, not to worry.
It's like a dripping tap though. Beth rings me and says Penny is too young to do the job, she is slapdash, she is careless. I defend the girl, I know she is good at her job, some of the people she cares for are severely impaired and the work is complex and she is universally praised in every other call.
The situation is not helped by the fact Jenny does not always remember things. She will tell Pen she doesn't fancy the salmon Beth has left, Pen makes her egg on toast and then Beth rings and plays hell because she hasn't has the meal that was left for her.Jenny then denies she has said she doesn't want the salmon. Beth questions everything Penny does and Jenny is getting the drift and starting to be cold to the girl too. I would take Penny out but there is nobody else to do those calls without sending Pen and another carer ten miles in opposite directions and depriving two sets of customers of the regular staff that they trust and are used to. The complaints are impossible to prove either way, each one not serious in itself but I wonder if the big one is coming, if soon the complaint will be something that puts us all through the wringer, scars Pen for life, and casts a pall of doubt on the agency as a whole.
I have tried to reason with Beth but she is totally unreasonable on the subject, almost frightening in her vitriol about this young girl that she has only met a handful of times. The package is shared with another agency and I rang their manager last week. It seems she is having similar problems and I learn that we are not the first agency to have been in there, in fact, we are pretty much the last ones covering that area who have not already handed the call back. The social worker is sympathetic but she has always found the daughter to be pleasant and reasonable, she only got the case recently and the worker who preceded her has moved on.
Penny was in tears today, she says she now wonders if this is the job for her. She says she has never been bright and the way she keeps making a mess of things in Jenny's is typical of her - she thought she was good at the job but maybe she should try at Tesco, she has heard they are taking on staff.
If I hand the call back I will feel we have all failed. Who will look after Jenny and who will defend us against Beth's condemnation? On the other hand I keep seeing Penny's face without it's trademark grin as she left the office today. I asked her if she wanted to come out of the call but she knows that will mean losing her other calls and she says she wants to stay - for now.
...She's picking on Penny and I don't know what to do.....