Yes it should have said chance, not change. Was in hospital at the time using a phone.
Had I been fitting the consumer unit I am sure I would have noticed the RCBO's were type AC curve B before fitting, but it was fitted by a scheme member mainly due to the work of removing the old one which was between the original ceiling and new false ceiling so rather an awkward job, every cable had to be extended with arms through holes cut in plaster board. With a mauled hand I was simply not dexterous enough to do the job myself.
I had collected all the materials likely to be required, and left him to do the job. And using type AC RCBO's is not against the regulations, and he did exactly what I asked, in theory I should have signed the design section, although I didn't, but I have the qualifications to design the installation and he was fully aware of that, he was my apprentice years ago.
But I made a mistake, I got the wrong RCBO's not him, and I have to either pay out for new RCBO's or live with the type AC. There is no way I can blame him for the error, it was my fault. I saw type B written on the packets and though Oh did not expect that type A would have been good enough, and in hind sight it should have rang alarm bells, and I should have opened a packet and looked at the logo on the device, as it seems type B RCBO's are not made as single module width so should have realised it was curve B not type B.
But if as an electrical engineer I can get it wrong when selecting materials, then clearly not a job for Joe public. Fair enough for the electrician to give a list to client and say can you pick up these, I have done that with other trades, he has said I have ordered all the bits at this place 20 miles away, can you pick them up and pay for them, and I have done just that, but the tradesman has selected the goods.