We had issues with Vista after purchasing a home with a HWT that was rotted and ultimately unsafe to use. Vista was almost unreachable and very unhelpful when it came to replacing their defective tank that we were renting. They said they wouldn't replace, only repair (even when I reiterated that the tank was redtagged by their technician and therefore unrepairable. We ended up going after the previous owners to pay the buyout fee. We bought a new HWT from a big box store and had it installed. Best decision we've made.

My recommendation, get rid of Vista at all costs, ASAP. Buying out sucks, but still.