block management

Tenancy Deposits

I have recently been charged extra costs by the flat management company because there were extra costs for them in managing the flats.
I have queried this because my flat is in a new build with only 6 flats but it is next but not adjoining a very old converted Mill with 50 flats. The management company have lumped together the charges for both buildings despite the fact that the old mill has a lift,an inadequate sewage system that often backs up,has needed decorated more often than my new build and has ongoing maintenance issues.

In your opinion do you think this is correct?.The new build has no lift, has never been decorated or had any repairs.Due to the lower number of residents it doesnt need any maintenance. The charges are £70pcm anyway so an extra bill for a shortfall is really sickening.

What to do?