Fire door has to be upgraded

[Lifestooshort71]

I live in a first-floor flat (which I own, block owned by freeholder and managed by management co) and 3 yrs ago another storey was added making the block 5 storeys high, 20 flats in total. At the time, a dividing wall was built around the stairwell and the flat at the top of each flight had their front doors changed to superior fire doors (at the freeholder’s expense).

I’ve just received an email, with an accompanying official report, saying my door now fails the fire regulations on 14 points and must be upgraded asap at my expense.
Surely if the freeholder hadn’t raised the height of the block this would be unnecessary? Or, if they paid for those on the stairwell then they should pay for mine? 3 flats on each floor affected = 12 in total (the ones on the new floor had them fitted at the time).

Would anybody have any experience of this and be able to advise whether it’s worth fighting who pays? I can’t afford a possible 4-figure sum and I’m seething that for 25 years my door was compliant! I’d be very grateful for any tips or suggestions.

Just check it really has to be
I live in an ex LA. It is 4/5 storey
of the 20 only 4 are still LA
they are upgrading the firedoors to current standards but it is optional for owners
at £4k each I don’t think there will be many takers
bit certainly not s requirement to upgrade to current standards

failing to meet current standards does not necessarily mean it has to be replaced.

Thank you, I thought because it failed on 14 points that would be a professional's advice but I'm a pessimist at heart. I might walk round to our local fire station later - think they might have some info.