I would first query the center, if I’m to be perfectly blunt, anonymous. It’s strictly against protocol to allow a service pokémon to evolve without an owner’s consent, as doing so risks rendering the pokémon unable to work. You may even be eligible for compensation, although I admit I’m less familiar with the laws about that.
Other than that, determine if your jolteon: A) can still perform the tasks he was meant to do for you, and B) is happy as a jolteon. If the answer to both is yes, then hopefully, things will be all right with some minor adjustments. Simply care for him the same way you would have if he were still an eevee, only increase his food and water, and keep him away from sensitive electronics until he can better control his abilities, as well as windows during thunderstorms from now onwards. If the answer to either question is no—especially the first question—then you should contact your local disability services organization immediately for a new service pokémon and support for your case.
Best of luck, anonymous, and I’m so sorry for what you’re going through.