The Risk Assessment Company say that the doors meet regulations but recommend fitting new doors! They aren't keen on taking on the Fure Safety Officer.
What a cop-out! They ought to be ashamed of themselves...
Can't really give you advice on whether the doors need changing or not - the Fire Officer has seen it and has made a professional judgement - I haven't and so cannot. However, if you have had your own professionals in and their judgement is different, they really should be obliged to support their opinions in front of the FSO. In my opinion, they shouldn't charge you for doing this either!
At the end of the day, if the doors are of a standard that would pass the old BS tests of 25 years ago, they're solid and 44mm thick or more, and there's no significant damage or alteration to door or frame, no glazing, vent grilles or thin panels, then you could probably construct a pretty strong argument that some surface-fitted fire and smoke seals would be enough to give performance near enough FD30S to mitigate the risk. The smoke seals are particularly important - the 25mm rebate was 'standard' for fire doors for years, but will make little difference to the smoke resistance of the doorset and in these circumstances that's really what you're after.