The £3000 outstanding amount should have been discovered by your solicitor when they did their searches for your purchase.
In a recent case I heard about the purchaser pursued the solicitor for the amount as it was their error. In the case in question the amount was £17K and the solicitor had to cough the lot.
I agree about the major works. They seem to come out of nowhere with no thought for the ability of the leaseholder’s ability to pay. I am also an artist (must be something in the NW6 air) and had no way of paying the £17K they were threatening for the EWI works.
We did fight it though and won with Camden cancelling the works which totally unneeded.
We all need to remember that Camden makes a per-centage commission on all works and are incentivised to spend as much as possible. Its a bloody scandal made even worse by the preferred contrator/partner system where there is no need to even have competitive bids. The sooner we all organise to take over the management of our properties the better.