I called them on a Saturday because my water heater started leaking. They called me back within 15 minutes and asked that I email some pictures of the tank and the sticker with the model number. I worried about my tank dying and spilling water on my neighbors in the apartments below but I told her Monday would be best. They said that a tech would visit Monday morning.
On Monday morning I had a tech at my property, to access the problem. They already had a replacement tank in case, if needed. They sent over an invoice that I agreed to and before the end of the day I had an entirely new system replaced and hassle-free. These guys do great work fast and affordable.