I'm still on a contract from 2016 or so with my mobile (cell) operator. 10 years of inflation, I pay basically nothing for some occassional data use and more voice than I could ever use.
Of course it irks them much to not be able to sell me less for more. But they can't do anything short of disconnecting me and that is unspeakable for a mobile operator.
I like this very much.
I used to have a good deal for years at Orange. They tried to get me on a new contract (slightly expensive) for a while, but at some point they just decommissioned the old program, basically they cancelled the old contracts and migrated everyone to the new plan. It was a minor change to me so went with it, then later they started to hike prices on the new plan, eventually I cancelled and left them after about 20 years.
You can probably do even better with a prepaid mvno at this point