Allianze Power Corp

I have a rental water heater with allianze that came with the house, I want to return it but they wont allow me to. I keep contacting them via email as that's the only option they give me. No one have any answers on the phone. They quoted me a buyout price of $2500. That's ridiculous. I told them I dont want to buyout the water heater as it does not work properly, its rusting from the top even though it's only 3 years old and hot water depletes after 1 shower. They wont tell me what this $2500 buy out price is based on. The will not produce the contract I signed. Funny thing is I'm and HVAC contractor, I'm not sure what to do with this water heater . I want to get rid of it.