NQ but Chartered Institute of Housing L3 qualified. If no section 20 consultation was undertaken as per Arthur Mills post above -
The most you can be charged is £250 and that is chargeable within 18 months of the work being completed.
(You said you think you're being charged for the whole lot as others are council tenants - Note. If the S20 had been carried out, you would pay a % of whatever your lease states, not for the complete roof (eg if 4 flats in the block, normally leasehold % would be 25% so you'd be charged 25% of the cost of the roof and if that % is over £250, a S20 consultation must be done for them to charge you)
If 3 years ago and no S20 notices received, they can't charge you.
Call/email so you have in writing, to the person that deals with leaseholders/
sends you your annual leasehold service charge invoice and ask them to provide evidence of the 3 x S20 notices that were sent to you.
If they can't, advise them of the situation and that they are providing incorrect information in connection with the sale of your property that is jeopardising the sale and they need to remedy the situation immediately.
If they fail to do so or are able to provide the 3 x S20 notices (must be all 3, not just the 1st one) which you did not receive, advise you are putting your complaint in writing and will be escalating the matter further to First Tier Tribunal for them to investigate.
I'm certain this course of action will remedy the situation, get confirmation in writing that no s20 was completed and so therefore, no charges are to be applied to you and you owe nothing.
The link above to Leasehold Advisory Service (lwww.lease-advi
ce.org) will tell you all the information as well.
(In addition, any monies owing as current leaseholder would normally need to be made prior to completion so will have to be dealt with before you sell but if you follow the above steps, this should be straightforward
and not delay your sale).
Hope that helps
1st April 2022