I’m know that is incorrect, you have to be qualified to do EICRs otherwise you could do your own which defeats the whole purpose.
I had a discussion with two electricians when this came in 5 years and although they were registered to do installations they were not registered to do EICRs. They were able to install new fuse boards and do an EIC and BC notification, but had to sign up separately to do EICRs.
There was a lot of confusion then between EIC and EICRs. both my electricians couldn’t understand why they were treated differently as both required the same tests, but nevertheless an EIC is not considered adequate.
There are companies that do EICRs for £99 in London. They only do these tests and don’t expect C3s to be rectified.
Just to add, you have an eicr cert, you have fixed the C2s. He can’t make you do the C3. If you have an EICR cert and receipts for rectifying the C2s then you are covered.