Whilst an RCD can be omitted for certain labelled sockets in a domestic property (with the associated cable protection) for a specific item. My green OSG, gives an example of a socket outlet for a freezer (yellow OSG might be different). I don't think its in the spirit of the reg' for an electric heater. Risk assessments cannot be used for domestic properties.
IMO converting the DP switch to socket 'alters' the use of the circuit, and the company should be complying with BS767 current at the time. I do not do EICR's, so I'll leave you guys to argue the coding. From my post #14, you'll see it is standard practise for this company to convert a DP to a socket, and there's no caveat in their answer . Which makes me wonder how many other properties they've done a similar thing.
Personally yellowvanman, you've done your job with your EICR and I would let this company come back and put their 'lazy' work (their description) right, after all it's their boast they 'cover the whole of Britain'. Up to the customer to resolve this issue with the company, I think.