Electrical Installation Condition Reports (EICR)

Hi, I would like a little guidance and advice about the new Electrical Installation Condition Reports (EICR), which become mandatory by the 1st April 2021 for existing tenancies.
I understand that there are 3 categories -
C1 – this indicates that danger exists and will need immediate attention.
C2 – this indicates that there is the potential for danger and advises urgent attention.
C3 – this indicates that the electrics pose no danger but still recommends the improvement of the electrical system.
If a C1 problem is found can the engineer disconnect the supply to stop any electrics being used until the fault is rectified? (This happened to the gas supply at the last gas safety inspection, leaving my tenants without heating and hot water). Does the engineer making the report have to carry out the repair immediately (i.e hold me to ransom and charge what they like) or can it be another electrician and within what timescale?
With C2’s is there a timescale within which the problem must be addressed?
Once C1 or C2 problems have been fixed, is another full or partial EICR required to confirm/log that the problem has been rectified correctly? Is this at full or a reduced pro rata cost?
With C3’s, is taking any remedial action voluntary? What happens if you do nothing?
Are subsequent EICR’s required every 5 years or every time a new tenancy starts, if sooner?
Would having a plastic clad consumer unit rather than metal (current standard) be classed as a C3?
Have you had any problems with your EICR? What seems to be the most common issues?
Many thanks, Alex.

C1. In my experience electrician will not cut off electric supply ( Gas is different eg. they can’t leave a gas leak).You have 28 days to rectify the issue. They will advise what needs to be done
C2 address within 28 days
If C1 and C2 are addressed you do need another EICR. We have not been charged for another certificate . If you use another electrician that’s another story( from the first EICR). Our electrician is fair but I can not speak to your electrician. They have amended the issue so they know what needs to change on the certificate.
C3 are recommendations and you do not need to do them ( they are not a legal requirement).
EICR every 5 years or what your electrician advises.
Plastic clad on a recent rewire is classed as a C3 ( our rewire was 2015 and April last year EICR was C3 for the unit). We did it anyway as the RCD was close to the front door. It’s a fire risk so in HMO if RCD is near emergency exit changing to metal box confers 30 minutes in event of fire. If you are a block of flats the Freeholder may advise it.

What seems to be the most common issues?
The RCD box. The legislation was introduced after research by the London Fire Brigade showed RCD to be the commonest source of fires in tower blocks.
C1 and C2 are usually rewires ( which will be advised at 20-25 year old installation or lots of additions).
We deal with HMO’s and no HMO’s. At a PIR a decade ago I changed electrician as our original retired. I booked in different electricians for different properties. If I failed I got a second opinion within 24 hours ( I did catch someone lying about the failure and reported the issue to NIECIC)