We had a partial re wire in April 2018 including new consumer unit (fuse box). We weren't overly happy with the work but it seemed ok. We received a test certificate, though this took some effort to get off them, including reporting to the governing body NICEIC.
Fast forward to 2 weeks ago. The plugs in the cellar and garage stopped working. They are on the same feed (we knew this at the time). Can't find the issue. Ask original electricians to come back but after 2 weeks of saying they'll come and not turning up I gave up. Different electrician came. He found this (see photo). The wires in the consumer unit (fuse box) are loose (or have come loose, it isn't clear but new electrician thinks they were never in properly). And one has set on fire. Thankfully the consumer unit has done what it should and cut it off, preventing a house fire.
WWYD? Report original electrician? This is the only evidence I have, didn't take photos before 2nd electrician fixed it.