...r und es ist narürluch alles abgesichert. ...
My guess is: This will be more expensive because new materials are also required. An electrician will certainly want to replace at least the "box," because he won't be able to fix it properly otherwise. To my knowledge, an electrician is always liable for the "entire system," even if he only changes minor things. At least that's how I understood the electricians who declined a renovation of my electrical system in the old building.
Unfortunately, this probably leads to extensive inspections (and then changes) in such situations.
The little cables look very thin; depending on the length of the wiring, those might have to be replaced as well. Underground cable? UV-resistant cable above ground in a protective conduit? The botched work will just continue elsewhere... No matter how cheap the place is/was, have it done properly and safely!!! A human life is very difficult to put a price on!