HMI Pheonix Contact PLC

I have a customer with a Phoenix Contact PLC connected to a HMI that is obsolete. My understanding is the Data is streamed to and from the PLC to the HMI and all the functions of the buttons is stored on the PLC. I have done PLC programming but never an HMI. Can anyone recommend a unit that is compatible with Phoenix contact PLC's that is easy to program?
Thanks

What HMI is it exactly ?
Maybe there is a new generation of the same product where you can migrate the old program to the new.