It may be appropriate to apply to The Leasehold Valuation Tribunal with your complaint(s) against the Freeholder.
You can also take the management of the property into your own hands by claiming the Right to Manage. This will give you, through a Right to Manage Company, all of the powers under the lease except forfeiture which remains with the Freeholder.
You could also consider exercising your right to purchase the freehold of the property.
Both the Right to Manage and the right to purchase require 50% participation of leaseholders and expert advice.