Why is your service such garbage in CA? I've went to multiple stores and the best they can say is "I can replace your SIM card." I am having this issue on multiple devices, there is only one commonality across all devices, and that is your horrible network. Can you fix this garbage? If not, I might as well search for the cheapest provider because paying this much for poor service is ridiculous.
As you know, there are two main carriers in the U.S./California: AT&T and Verizon; there is also T-Mobile to consider. My experience in California is that Verizon is one of, if not the best!
I'd ask your colleagues in Sacramento & Red Bluff which service they have the best luck with and go with that. - - I used to live in Redding way back when... nice area for sure, although a tad hot this time of year! - Good luck getting better service!