I feel for you and your family having to go through this sh!t from a bunch of cowboys. Its people like this that give sparks a bad name, many of whom take pride in their work. Something needs to be done but, I feel taling to Motability will just fall on death ears sadly.
Anyhow at least Ive been of some help, if only from a distance.
Your earlier post stating the guy didn’t know where simple wiring goes for a CT clamp and having to go on the phone for 45 ninutes, screams not competant and not very qualified.
The fact he told you there is a switch in the meter that will trip if there’s a problem, is so very very wrong. Regulations are there to be adhered to and they clearly state in black and white load curtailment can be used as a means of derating maximum demand end of. I would imagine the guy was refering to the 100A isolator, which is a means of isolating the supply, to enable safe working or in an emergercy from the consumers side of the meter, rather than a protective device. In anycase most houses are getting 80A cut-outs from the DNO, so what will a 100A isolator protect exactly!
Hopefully you get it all sorted soon so you can put it behind you 🙂