Although i wholeheartedly agree,with the sympathies expressed,it only strengthens my original belief,that relying on people guaranteed by an organisation,that is paid by said people,is flawed.....and the same is true,for checkatrader
The painful truth is,that without any written schedule/contract or agreement,most of what has been described and shown,could easily be argued away,and the liability shifted.
If as described,your situation is worthy of sympathy,but aesthetics aside,i would be more concerned regarding other,more fundamental errors,hidden now,such as why there are nervous RCD's,etc.
As suggested,a recommended electrician,from out of the area,if needed,paid independently,to assess where you are at this point.