As a caregiver who worked for a particular company and has switched to a company that better meets my needs, client wants to switch company as well so I can continue to be his caregiver. POA keeps stopping the process for unknown reasons and client has no power to switch.
Since the client can make decisions, I think the crux is your observation that the client fears the POA. The question would then be why (a) the fear exists (b) why the POA is even involved in selecting a caregiving agency (c) whether the client is capable of standing up for his own rights and selecting someone else as his proxy under the POA and (d) why the client "has no power."
There's more to this situation than meets the eye, and it seems to be between the client and the caregiver. Be careful of becoming dragged into a power struggle between these two.
A guardian could determine where the person lives and to hire and fire help, etc.
Is anyone a guardian? Is this person competent to make decisions (in the legal sense -- has a court ever declared him incompetent)?
It would seem that this person could decide for himself who he wanted for a caregiver. But there may be more to this than appears on the surface. Perhaps, for example, the POA has looked at legal ramifications of ending the contract with the first company and going with one of their former employees to a new company.
I did contract work in the information systems area for many years, usually through a contractor company. There were rules prohibiting me from working for a client for a period of time (at least a year) if they had placed me at the client and I left their company. It can get kind of tricky.
So without knowing what contracts you have signed with your old company, or what contracts your client might have signed, I can't say the POA has no business in this issue. There may be some legal concerns.
It is sad that you cannot serve this client at this time. Can you discuss this issue with the POA? Perhaps after a period of time the POA would be able and willing to re-hire you.