Hi Unhappy, welcome to the forum.

Firstly I have to ask what possessed you to get a second company in to do another certificate when the place had already failed and the required remedial work hadn't been finished?

There's recently been a new ammendment (amdt 8) in the domestic installation regulations so it's possible the first CoC was done before the changes came in and the second one was done after. I assume you have the two lists of remedial work required so tell us what the differences are and we may be able to comment.