Had an issue with the house I bought recently. Plumber hired by previous owner installed some parts backwards. Valves for a tankless water heater that allowed you to flush it with a cleaner had the side connection on the opposite side of the heater from the main shut off. Instead of hiring someone to fix it, just called the company and asked them to fix their mistake. They have us scheduled next week.
Just a side note, if you ever buy a house, requesting documentation on who did what to your future house is well worth it. If it was DIY, just make sure they say it was, and ask them if it was done up to code and inspected.
