Utility can’t be expected to abide by decades long mutual agreements just because some lady doesn’t want to accept their new deal without negotiation.
There is no such agreement.
What mutual agreements would those be? Was there a mutual agreement that the utility would never upgrade their (THEIR not HER) equipment? Does this imaginary mutual agreement apply to generation mix as well so that they would never switch to cheaper natural gas combustion turbines, etc.? How about transmission and power lines? Did those imaginary agreements cover extending their grid to new customers?
The only mutual agreement between customers and utilities is that the utilities provide power and the customer pays for it.